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  <a href="http://codemirror.net"><h1>CodeMirror</h1><img id=logo src="logo.png"></a>
  <ul>
    <li><a href="../index.html">Home</a></li>
    <li><a href="#overview" class=active data-default="true">Manual</a></li>
    <li><a href="https://github.com/codemirror/codemirror">Code</a></li>
  </ul>
  <ul>
    <li><a href="#usage">Basic Usage</a></li>
    <li><a href="#config">Configuration</a></li>
    <li><a href="#events">Events</a></li>
    <li><a href="#keymaps">Key maps</a></li>
    <li><a href="#commands">Commands</a></li>
    <li><a href="#styling">Customized Styling</a></li>
    <li><a href="#api">Programming API</a>
      <ul>
        <li><a href="#api_constructor">Constructor</a></li>
        <li><a href="#api_content">Content manipulation</a></li>
        <li><a href="#api_selection">Selection</a></li>
        <li><a href="#api_configuration">Configuration</a></li>
        <li><a href="#api_doc">Document management</a></li>
        <li><a href="#api_history">History</a></li>
        <li><a href="#api_marker">Text-marking</a></li>
        <li><a href="#api_decoration">Widget, gutter, and decoration</a></li>
        <li><a href="#api_sizing">Sizing, scrolling, and positioning</a></li>
        <li><a href="#api_mode">Mode, state, and tokens</a></li>
        <li><a href="#api_misc">Miscellaneous methods</a></li>
        <li><a href="#api_static">Static properties</a></li>
      </ul>
    </li>
    <li><a href="#addons">Addons</a></li>
    <li><a href="#modeapi">Writing CodeMirror Modes</a></li>
    <li><a href="#vimapi">Vim Mode API</a>
      <ul>
        <li><a href="#vimapi_configuration">Configuration</a></li>
        <li><a href="#vimapi_extending">Extending VIM</a></li>
      </ul>
    </li>
  </ul>
</div>

<article>

  <section class=first id=overview>
    <h2 style="position: relative">
      User manual and reference guide
      <span style="color: #888; font-size: 1rem; position: absolute; right: 0; bottom: 0">version 5.30.0</span>
    </h2>

    <p>CodeMirror is a code-editor component that can be embedded in
      Web pages. The core library provides <em>only</em> the editor
      component, no accompanying buttons, auto-completion, or other IDE
      functionality. It does provide a rich API on top of which such
      functionality can be straightforwardly implemented. See
      the <a href="#addons">addons</a> included in the distribution,
      and the <a href="https://github.com/codemirror/CodeMirror/wiki/CodeMirror-addons">list
        of externally hosted addons</a>, for reusable
      implementations of extra features.</p>

    <p>CodeMirror works with language-specific modes. Modes are
      JavaScript programs that help color (and optionally indent) text
      written in a given language. The distribution comes with a number
      of modes (see the <a href="../mode"><code>mode/</code></a>
      directory), and it isn't hard to <a href="#modeapi">write new
        ones</a> for other languages.</p>
  </section>

  <section id=usage>
    <h2>Basic Usage</h2>

    <p>The easiest way to use CodeMirror is to simply load the script
      and style sheet found under <code>lib/</code> in the distribution,
      plus a mode script from one of the <code>mode/</code> directories.
      For example:</p>

    <pre data-lang="text/html">&lt;script src="lib/codemirror.js">&lt;/script>
&lt;link rel="stylesheet" href="lib/codemirror.css">
&lt;script src="mode/javascript/javascript.js">&lt;/script></pre>

    <p>(Alternatively, use a module loader. <a href="#modloader">More
      about that later.</a>)</p>

    <p>Having done this, an editor instance can be created like
      this:</p>

    <pre data-lang="javascript">var myCodeMirror = CodeMirror(document.body);</pre>

    <p>The editor will be appended to the document body, will start
      empty, and will use the mode that we loaded. To have more control
      over the new editor, a configuration object can be passed
      to <a href="#CodeMirror"><code>CodeMirror</code></a> as a second
      argument:</p>

    <pre data-lang="javascript">var myCodeMirror = CodeMirror(document.body, {
  value: "function myScript(){return 100;}\n",
  mode:  "javascript"
});</pre>

    <p>This will initialize the editor with a piece of code already in
      it, and explicitly tell it to use the JavaScript mode (which is
      useful when multiple modes are loaded).
      See <a href="#config">below</a> for a full discussion of the
      configuration options that CodeMirror accepts.</p>

    <p>In cases where you don't want to append the editor to an
      element, and need more control over the way it is inserted, the
      first argument to the <code>CodeMirror</code> function can also
      be a function that, when given a DOM element, inserts it into the
      document somewhere. This could be used to, for example, replace a
      textarea with a real editor:</p>

    <pre data-lang="javascript">var myCodeMirror = CodeMirror(function(elt) {
  myTextArea.parentNode.replaceChild(elt, myTextArea);
}, {value: myTextArea.value});</pre>

    <p>However, for this use case, which is a common way to use
      CodeMirror, the library provides a much more powerful
      shortcut:</p>

    <pre data-lang="javascript">var myCodeMirror = CodeMirror.fromTextArea(myTextArea);</pre>

    <p>This will, among other things, ensure that the textarea's value
      is updated with the editor's contents when the form (if it is part
      of a form) is submitted. See the <a href="#fromTextArea">API
        reference</a> for a full description of this method.</p>

    <h3 id=modloader>Module loaders</h3>

    <p>The files in the CodeMirror distribution contain shims for
      loading them (and their dependencies) in AMD or CommonJS
      environments. If the variables <code>exports</code>
      and <code>module</code> exist and have type object, CommonJS-style
      require will be used. If not, but there is a
      function <code>define</code> with an <code>amd</code> property
      present, AMD-style (RequireJS) will be used.</p>

    <p>It is possible to
      use <a href="http://browserify.org/">Browserify</a> or similar
      tools to statically build modules using CodeMirror. Alternatively,
      use <a href="http://requirejs.org/">RequireJS</a> to dynamically
      load dependencies at runtime. Both of these approaches have the
      advantage that they don't use the global namespace and can, thus,
      do things like load multiple versions of CodeMirror alongside each
      other.</p>

    <p>Here's a simple example of using RequireJS to load CodeMirror:</p>

    <pre data-lang="javascript">require([
  "cm/lib/codemirror", "cm/mode/htmlmixed/htmlmixed"
], function(CodeMirror) {
  CodeMirror.fromTextArea(document.getElementById("code"), {
    lineNumbers: true,
    mode: "htmlmixed"
  });
});</pre>

    <p>It will automatically load the modes that the mixed HTML mode
      depends on (XML, JavaScript, and CSS). Do <em>not</em> use
      RequireJS' <code>paths</code> option to configure the path to
      CodeMirror, since it will break loading submodules through
      relative paths. Use
      the <a href="http://requirejs.org/docs/api.html#packages"><code>packages</code></a>
      configuration option instead, as in:</p>

    <pre data-lang=javascript>require.config({
  packages: [{
    name: "codemirror",
    location: "../path/to/codemirror",
    main: "lib/codemirror"
  }]
});</pre>

  </section>

  <section id=config>
    <h2>Configuration</h2>

    <p>Both the <a href="#CodeMirror"><code>CodeMirror</code></a>
      function and its <code>fromTextArea</code> method take as second
      (optional) argument an object containing configuration options.
      Any option not supplied like this will be taken
      from <a href="#defaults"><code>CodeMirror.defaults</code></a>, an
      object containing the default options. You can update this object
      to change the defaults on your page.</p>

    <p>Options are not checked in any way, so setting bogus option
      values is bound to lead to odd errors.</p>

    <p>These are the supported options:</p>

    <dl>
      <dt id="option_value"><code><strong>value</strong>: string|CodeMirror.Doc</code></dt>
      <dd>The starting value of the editor. Can be a string, or
        a <a href="#api_doc">document object</a>.
      </dd>

      <dt id="option_mode"><code><strong>mode</strong>: string|object</code></dt>
      <dd>The mode to use. When not given, this will default to the
        first mode that was loaded. It may be a string, which either
        simply names the mode or is
        a <a href="http://en.wikipedia.org/wiki/MIME">MIME</a> type
        associated with the mode. Alternatively, it may be an object
        containing configuration options for the mode, with
        a <code>name</code> property that names the mode (for
        example <code>{name: "javascript", json: true}</code>). The demo
        pages for each mode contain information about what configuration
        parameters the mode supports. You can ask CodeMirror which modes
        and MIME types have been defined by inspecting
        the <code>CodeMirror.modes</code>
        and <code>CodeMirror.mimeModes</code> objects. The first maps
        mode names to their constructors, and the second maps MIME types
        to mode specs.
      </dd>

      <dt id="option_lineSeparator"><code><strong>lineSeparator</strong>: string|null</code></dt>
      <dd>Explicitly set the line separator for the editor. By default
        (value <code>null</code>), the document will be split on CRLFs
        as well as lone CRs and LFs, and a single LF will be used as
        line separator in all output (such
        as <a href="#getValue"><code>getValue</code></a>). When a
        specific string is given, lines will only be split on that
        string, and output will, by default, use that same
        separator.
      </dd>

      <dt id="option_theme"><code><strong>theme</strong>: string</code></dt>
      <dd>The theme to style the editor with. You must make sure the
        CSS file defining the corresponding <code>.cm-s-[name]</code>
        styles is loaded (see
        the <a href="../theme"><code>theme</code></a> directory in the
        distribution). The default is <code>"default"</code>, for which
        colors are included in <code>codemirror.css</code>. It is
        possible to use multiple theming classes at once—for
        example <code>"foo bar"</code> will assign both
        the <code>cm-s-foo</code> and the <code>cm-s-bar</code> classes
        to the editor.
      </dd>

      <dt id="option_indentUnit"><code><strong>indentUnit</strong>: integer</code></dt>
      <dd>How many spaces a block (whatever that means in the edited
        language) should be indented. The default is 2.
      </dd>

      <dt id="option_smartIndent"><code><strong>smartIndent</strong>: boolean</code></dt>
      <dd>Whether to use the context-sensitive indentation that the
        mode provides (or just indent the same as the line before).
        Defaults to true.
      </dd>

      <dt id="option_tabSize"><code><strong>tabSize</strong>: integer</code></dt>
      <dd>The width of a tab character. Defaults to 4.</dd>

      <dt id="option_indentWithTabs"><code><strong>indentWithTabs</strong>: boolean</code></dt>
      <dd>Whether, when indenting, the first N*<code>tabSize</code>
        spaces should be replaced by N tabs. Default is false.
      </dd>

      <dt id="option_electricChars"><code><strong>electricChars</strong>: boolean</code></dt>
      <dd>Configures whether the editor should re-indent the current
        line when a character is typed that might change its proper
        indentation (only works if the mode supports indentation).
        Default is true.
      </dd>

      <dt id="option_specialChars"><code><strong>specialChars</strong>: RegExp</code></dt>
      <dd>A regular expression used to determine which characters
        should be replaced by a
        special <a href="#option_specialCharPlaceholder">placeholder</a>.
        Mostly useful for non-printing special characters. The default
        is <code>/[\u0000-\u001f\u007f-\u009f\u00ad\u061c\u200b-\u200f\u2028\u2029\ufeff]/</code>.
      </dd>
      <dt id="option_specialCharPlaceholder"><code><strong>specialCharPlaceholder</strong>:
        function(char) → Element</code></dt>
      <dd>A function that, given a special character identified by
        the <a href="#option_specialChars"><code>specialChars</code></a>
        option, produces a DOM node that is used to represent the
        character. By default, a red dot (<span style="color: red">•</span>)
        is shown, with a title tooltip to indicate the character code.
      </dd>

      <dt id="option_rtlMoveVisually"><code><strong>rtlMoveVisually</strong>: boolean</code></dt>
      <dd>Determines whether horizontal cursor movement through
        right-to-left (Arabic, Hebrew) text is visual (pressing the left
        arrow moves the cursor left) or logical (pressing the left arrow
        moves to the next lower index in the string, which is visually
        right in right-to-left text). The default is <code>false</code>
        on Windows, and <code>true</code> on other platforms.
      </dd>

      <dt id="option_keyMap"><code><strong>keyMap</strong>: string</code></dt>
      <dd>Configures the key map to use. The default
        is <code>"default"</code>, which is the only key map defined
        in <code>codemirror.js</code> itself. Extra key maps are found in
        the <a href="../keymap"><code>key map</code></a> directory. See
        the <a href="#keymaps">section on key maps</a> for more
        information.
      </dd>

      <dt id="option_extraKeys"><code><strong>extraKeys</strong>: object</code></dt>
      <dd>Can be used to specify extra key bindings for the editor,
        alongside the ones defined
        by <a href="#option_keyMap"><code>keyMap</code></a>. Should be
        either null, or a valid <a href="#keymaps">key map</a> value.
      </dd>

      <dt id="option_configureMouse"><code><strong>configureMouse</strong>: fn(cm: CodeMirror, repeat: "single" |
        "double" | "triple", event: Event) → Object</code></dt>
      <dd>Allows you to configure the behavior of mouse selection and
        dragging. The function is called when the left mouse button is
        pressed. The returned object may have the following properties:
        <dl>
          <dt><code><strong>unit</strong>: "char" | "word" | "line" | "rectangle" | fn(CodeMirror, Pos) → {from: Pos,
            to: Pos}</code></dt>
          <dd>The unit by which to select. May be one of the built-in
            units, or a function that takes a position and returns a
            range around that, for a custom unit.
          </dd>
          <dt><code><strong>extend</strong>: bool</code></dt>
          <dd>Whether to extend the existing selection range or start a new one.</dd>
          <dt><code><strong>addNew</strong>: bool</code></dt>
          <dd>When enabled, this adds a new range to the existing selection, rather than replacing it.</dd>
          <dt><code><strong>moveOnDrag</strong>: bool</code></dt>
          <dd>When the mouse even drags content around inside the
            editor, this controls whether it is copied (false) or moved
            (true).
          </dt>
        </dl>
      </dd>

      <dt id="option_lineWrapping"><code><strong>lineWrapping</strong>: boolean</code></dt>
      <dd>Whether CodeMirror should scroll or wrap for long lines.
        Defaults to <code>false</code> (scroll).
      </dd>

      <dt id="option_lineNumbers"><code><strong>lineNumbers</strong>: boolean</code></dt>
      <dd>Whether to show line numbers to the left of the editor.</dd>

      <dt id="option_firstLineNumber"><code><strong>firstLineNumber</strong>: integer</code></dt>
      <dd>At which number to start counting lines. Default is 1.</dd>

      <dt id="option_lineNumberFormatter"><code><strong>lineNumberFormatter</strong>: function(line: integer) →
        string</code></dt>
      <dd>A function used to format line numbers. The function is
        passed the line number, and should return a string that will be
        shown in the gutter.
      </dd>

      <dt id="option_gutters"><code><strong>gutters</strong>: array&lt;string&gt;</code></dt>
      <dd>Can be used to add extra gutters (beyond or instead of the
        line number gutter). Should be an array of CSS class names, each
        of which defines a <code>width</code> (and optionally a
        background), and which will be used to draw the background of
        the gutters. <em>May</em> include
        the <code>CodeMirror-linenumbers</code> class, in order to
        explicitly set the position of the line number gutter (it will
        default to be to the right of all other gutters). These class
        names are the keys passed
        to <a href="#setGutterMarker"><code>setGutterMarker</code></a>.
      </dd>

      <dt id="option_fixedGutter"><code><strong>fixedGutter</strong>: boolean</code></dt>
      <dd>Determines whether the gutter scrolls along with the content
        horizontally (false) or whether it stays fixed during horizontal
        scrolling (true, the default).
      </dd>

      <dt id="option_scrollbarStyle"><code><strong>scrollbarStyle</strong>: string</code></dt>
      <dd>Chooses a scrollbar implementation. The default
        is <code>"native"</code>, showing native scrollbars. The core
        library also provides the <code>"null"</code> style, which
        completely hides the
        scrollbars. <a href="#addon_simplescrollbars">Addons</a> can
        implement additional scrollbar models.
      </dd>

      <dt id="option_coverGutterNextToScrollbar"><code><strong>coverGutterNextToScrollbar</strong>: boolean</code></dt>
      <dd>When <a href="#option_fixedGutter"><code>fixedGutter</code></a>
        is on, and there is a horizontal scrollbar, by default the
        gutter will be visible to the left of this scrollbar. If this
        option is set to true, it will be covered by an element with
        class <code>CodeMirror-gutter-filler</code>.
      </dd>

      <dt id="option_inputStyle"><code><strong>inputStyle</strong>: string</code></dt>
      <dd>Selects the way CodeMirror handles input and focus. The core
        library defines the <code>"textarea"</code>
        and <code>"contenteditable"</code> input models. On mobile
        browsers, the default is <code>"contenteditable"</code>. On
        desktop browsers, the default is <code>"textarea"</code>.
        Support for IME and screen readers is better in
        the <code>"contenteditable"</code> model. The intention is to
        make it the default on modern desktop browsers in the
        future.
      </dd>

      <dt id="option_readOnly"><code><strong>readOnly</strong>: boolean|string</code></dt>
      <dd>This disables editing of the editor content by the user. If
        the special value <code>"nocursor"</code> is given (instead of
        simply <code>true</code>), focusing of the editor is also
        disallowed.
      </dd>

      <dt id="option_showCursorWhenSelecting"><code><strong>showCursorWhenSelecting</strong>: boolean</code></dt>
      <dd>Whether the cursor should be drawn when a selection is
        active. Defaults to false.
      </dd>

      <dt id="option_lineWiseCopyCut"><code><strong>lineWiseCopyCut</strong>: boolean</code></dt>
      <dd>When enabled, which is the default, doing copy or cut when
        there is no selection will copy or cut the whole lines that have
        cursors on them.
      </dd>

      <dt id="option_pasteLinesPerSelection"><code><strong>pasteLinesPerSelection</strong>: boolean</code></dt>
      <dd>When pasting something from an external source (not from the
        editor itself), if the number of lines matches the number of
        selection, CodeMirror will by default insert one line per
        selection. You can set this to <code>false</code> to disable
        that behavior.
      </dd>

      <dt id="option_undoDepth"><code><strong>undoDepth</strong>: integer</code></dt>
      <dd>The maximum number of undo levels that the editor stores.
        Note that this includes selection change events. Defaults to
        200.
      </dd>

      <dt id="option_historyEventDelay"><code><strong>historyEventDelay</strong>: integer</code></dt>
      <dd>The period of inactivity (in milliseconds) that will cause a
        new history event to be started when typing or deleting.
        Defaults to 1250.
      </dd>

      <dt id="option_tabindex"><code><strong>tabindex</strong>: integer</code></dt>
      <dd>The <a href="http://www.w3.org/TR/html401/interact/forms.html#adef-tabindex">tab
        index</a> to assign to the editor. If not given, no tab index
        will be assigned.
      </dd>

      <dt id="option_autofocus"><code><strong>autofocus</strong>: boolean</code></dt>
      <dd>Can be used to make CodeMirror focus itself on
        initialization. Defaults to off.
        When <a href="#fromTextArea"><code>fromTextArea</code></a> is
        used, and no explicit value is given for this option, it will be
        set to true when either the source textarea is focused, or it
        has an <code>autofocus</code> attribute and no other element is
        focused.
      </dd>
    </dl>

    <p>Below this a few more specialized, low-level options are
      listed. These are only useful in very specific situations, you
      might want to skip them the first time you read this manual.</p>

    <dl>
      <dt id="option_dragDrop"><code><strong>dragDrop</strong>: boolean</code></dt>
      <dd>Controls whether drag-and-drop is enabled. On by default.</dd>

      <dt id="option_allowDropFileTypes"><code><strong>allowDropFileTypes</strong>: array&lt;string&gt;</code></dt>
      <dd>When set (default is <code>null</code>) only files whose
        type is in the array can be dropped into the editor. The strings
        should be MIME types, and will be checked against
        the <a href="https://w3c.github.io/FileAPI/#dfn-type"><code>type</code></a>
        of the <code>File</code> object as reported by the browser.
      </dd>

      <dt id="option_cursorBlinkRate"><code><strong>cursorBlinkRate</strong>: number</code></dt>
      <dd>Half-period in milliseconds used for cursor blinking. The default blink
        rate is 530ms. By setting this to zero, blinking can be disabled. A
        negative value hides the cursor entirely.
      </dd>

      <dt id="option_cursorScrollMargin"><code><strong>cursorScrollMargin</strong>: number</code></dt>
      <dd>How much extra space to always keep above and below the
        cursor when approaching the top or bottom of the visible view in
        a scrollable document. Default is 0.
      </dd>

      <dt id="option_cursorHeight"><code><strong>cursorHeight</strong>: number</code></dt>
      <dd>Determines the height of the cursor. Default is 1, meaning
        it spans the whole height of the line. For some fonts (and by
        some tastes) a smaller height (for example <code>0.85</code>),
        which causes the cursor to not reach all the way to the bottom
        of the line, looks better
      </dd>

      <dt id="option_resetSelectionOnContextMenu"><code><strong>resetSelectionOnContextMenu</strong>: boolean</code>
      </dt>
      <dd>Controls whether, when the context menu is opened with a
        click outside of the current selection, the cursor is moved to
        the point of the click. Defaults to <code>true</code>.
      </dd>

      <dt id="option_workTime"><code id="option_wordkDelay"><strong>workTime</strong>, <strong>workDelay</strong>:
        number</code></dt>
      <dd>Highlighting is done by a pseudo background-thread that will
        work for <code>workTime</code> milliseconds, and then use
        timeout to sleep for <code>workDelay</code> milliseconds. The
        defaults are 200 and 300, you can change these options to make
        the highlighting more or less aggressive.
      </dd>

      <dt id="option_pollInterval"><code><strong>pollInterval</strong>: number</code></dt>
      <dd>Indicates how quickly CodeMirror should poll its input
        textarea for changes (when focused). Most input is captured by
        events, but some things, like IME input on some browsers, don't
        generate events that allow CodeMirror to properly detect it.
        Thus, it polls. Default is 100 milliseconds.
      </dd>

      <dt id="option_flattenSpans"><code><strong>flattenSpans</strong>: boolean</code></dt>
      <dd>By default, CodeMirror will combine adjacent tokens into a
        single span if they have the same class. This will result in a
        simpler DOM tree, and thus perform better. With some kinds of
        styling (such as rounded corners), this will change the way the
        document looks. You can set this option to false to disable this
        behavior.
      </dd>

      <dt id="option_addModeClass"><code><strong>addModeClass</strong>: boolean</code></dt>
      <dd>When enabled (off by default), an extra CSS class will be
        added to each token, indicating the
        (<a href="#innerMode">inner</a>) mode that produced it, prefixed
        with <code>"cm-m-"</code>. For example, tokens from the XML mode
        will get the <code>cm-m-xml</code> class.
      </dd>

      <dt id="option_maxHighlightLength"><code><strong>maxHighlightLength</strong>: number</code></dt>
      <dd>When highlighting long lines, in order to stay responsive,
        the editor will give up and simply style the rest of the line as
        plain text when it reaches a certain position. The default is
        10 000. You can set this to <code>Infinity</code> to turn off
        this behavior.
      </dd>

      <dt id="option_viewportMargin"><code><strong>viewportMargin</strong>: integer</code></dt>
      <dd>Specifies the amount of lines that are rendered above and
        below the part of the document that's currently scrolled into
        view. This affects the amount of updates needed when scrolling,
        and the amount of work that such an update does. You should
        usually leave it at its default, 10. Can be set
        to <code>Infinity</code> to make sure the whole document is
        always rendered, and thus the browser's text search works on it.
        This <em>will</em> have bad effects on performance of big
        documents.
      </dd>
    </dl>
  </section>

  <section id=events>
    <h2>Events</h2>

    <p>Various CodeMirror-related objects emit events, which allow
      client code to react to various situations. Handlers for such
      events can be registered with the <a href="#on"><code>on</code></a>
      and <a href="#off"><code>off</code></a> methods on the objects
      that the event fires on. To fire your own events,
      use <code>CodeMirror.signal(target, name, args...)</code>,
      where <code>target</code> is a non-DOM-node object.</p>

    <p>An editor instance fires the following events.
      The <code>instance</code> argument always refers to the editor
      itself.</p>

    <dl>
      <dt id="event_change"><code><strong>"change"</strong> (instance: CodeMirror, changeObj: object)</code></dt>
      <dd>Fires every time the content of the editor is changed.
        The <code>changeObj</code> is a <code>{from, to, text, removed,
          origin}</code> object containing information about the changes
        that occurred as second argument. <code>from</code>
        and <code>to</code> are the positions (in the pre-change
        coordinate system) where the change started and ended (for
        example, it might be <code>{ch:0, line:18}</code> if the
        position is at the beginning of line #19). <code>text</code> is
        an array of strings representing the text that replaced the
        changed range (split by line). <code>removed</code> is the text
        that used to be between <code>from</code> and <code>to</code>,
        which is overwritten by this change. This event is
        fired <em>before</em> the end of
        an <a href="#operation">operation</a>, before the DOM updates
        happen.
      </dd>

      <dt id="event_changes"><code><strong>"changes"</strong> (instance: CodeMirror, changes:
        array&lt;object&gt;)</code></dt>
      <dd>Like the <a href="#event_change"><code>"change"</code></a>
        event, but batched per <a href="#operation">operation</a>,
        passing an array containing all the changes that happened in the
        operation. This event is fired after the operation finished, and
        display changes it makes will trigger a new operation.
      </dd>

      <dt id="event_beforeChange"><code><strong>"beforeChange"</strong> (instance: CodeMirror, changeObj: object)</code>
      </dt>
      <dd>This event is fired before a change is applied, and its
        handler may choose to modify or cancel the change.
        The <code>changeObj</code> object
        has <code>from</code>, <code>to</code>, and <code>text</code>
        properties, as with
        the <a href="#event_change"><code>"change"</code></a> event. It
        also has a <code>cancel()</code> method, which can be called to
        cancel the change, and, <strong>if</strong> the change isn't
        coming from an undo or redo event, an <code>update(from, to,
          text)</code> method, which may be used to modify the change.
        Undo or redo changes can't be modified, because they hold some
        metainformation for restoring old marked ranges that is only
        valid for that specific change. All three arguments
        to <code>update</code> are optional, and can be left off to
        leave the existing value for that field
        intact. <strong>Note:</strong> you may not do anything from
        a <code>"beforeChange"</code> handler that would cause changes
        to the document or its visualization. Doing so will, since this
        handler is called directly from the bowels of the CodeMirror
        implementation, probably cause the editor to become
        corrupted.
      </dd>

      <dt id="event_cursorActivity"><code><strong>"cursorActivity"</strong> (instance: CodeMirror)</code></dt>
      <dd>Will be fired when the cursor or selection moves, or any
        change is made to the editor content.
      </dd>

      <dt id="event_keyHandled"><code><strong>"keyHandled"</strong> (instance: CodeMirror, name: string, event:
        Event)</code></dt>
      <dd>Fired after a key is handled through a
        key map. <code>name</code> is the name of the handled key (for
        example <code>"Ctrl-X"</code> or <code>"'q'"</code>),
        and <code>event</code> is the DOM <code>keydown</code>
        or <code>keypress</code> event.
      </dd>

      <dt id="event_inputRead"><code><strong>"inputRead"</strong> (instance: CodeMirror, changeObj: object)</code></dt>
      <dd>Fired whenever new input is read from the hidden textarea
        (typed or pasted by the user).
      </dd>

      <dt id="event_electricInput"><code><strong>"electricInput"</strong> (instance: CodeMirror, line: integer)</code>
      </dt>
      <dd>Fired if text input matched the
        mode's <a href="#option_electricChars">electric</a> patterns,
        and this caused the line's indentation to change.
      </dd>

      <dt id="event_beforeSelectionChange"><code><strong>"beforeSelectionChange"</strong> (instance: CodeMirror, obj:
        {ranges, origin, update})</code></dt>
      <dd>This event is fired before the selection is moved. Its
        handler may inspect the set of selection ranges, present as an
        array of <code>{anchor, head}</code> objects in
        the <code>ranges</code> property of the <code>obj</code>
        argument, and optionally change them by calling
        the <code>update</code> method on this object, passing an array
        of ranges in the same format. The object also contains
        an <code>origin</code> property holding the origin string passed
        to the selection-changing method, if any. Handlers for this
        event have the same restriction
        as <a href="#event_beforeChange"><code>"beforeChange"</code></a>
        handlers — they should not do anything to directly update the
        state of the editor.
      </dd>

      <dt id="event_viewportChange"><code><strong>"viewportChange"</strong> (instance: CodeMirror, from: number, to:
        number)</code></dt>
      <dd>Fires whenever the <a href="#getViewport">view port</a> of
        the editor changes (due to scrolling, editing, or any other
        factor). The <code>from</code> and <code>to</code> arguments
        give the new start and end of the viewport.
      </dd>

      <dt id="event_swapDoc"><code><strong>"swapDoc"</strong> (instance: CodeMirror, oldDoc: Doc)</code></dt>
      <dd>This is signalled when the editor's document is replaced
        using the <a href="#swapDoc"><code>swapDoc</code></a>
        method.
      </dd>

      <dt id="event_gutterClick"><code><strong>"gutterClick"</strong> (instance: CodeMirror, line: integer, gutter:
        string, clickEvent: Event)</code></dt>
      <dd>Fires when the editor gutter (the line-number area) is
        clicked. Will pass the editor instance as first argument, the
        (zero-based) number of the line that was clicked as second
        argument, the CSS class of the gutter that was clicked as third
        argument, and the raw <code>mousedown</code> event object as
        fourth argument.
      </dd>

      <dt id="event_gutterContextMenu"><code><strong>"gutterContextMenu"</strong> (instance: CodeMirror, line: integer,
        gutter: string, contextMenu: Event: Event)</code></dt>
      <dd>Fires when the editor gutter (the line-number area)
        receives a <code>contextmenu</code> event. Will pass the editor
        instance as first argument, the (zero-based) number of the line
        that was clicked as second argument, the CSS class of the
        gutter that was clicked as third argument, and the raw
        <code>contextmenu</code> mouse event object as fourth argument.
        You can <code>preventDefault</code> the event, to signal that
        CodeMirror should do no further handling.
      </dd>

      <dt id="event_focus"><code><strong>"focus"</strong> (instance: CodeMirror, event: Event)</code></dt>
      <dd>Fires whenever the editor is focused.</dd>

      <dt id="event_blur"><code><strong>"blur"</strong> (instance: CodeMirror, event: Event)</code></dt>
      <dd>Fires whenever the editor is unfocused.</dd>

      <dt id="event_scroll"><code><strong>"scroll"</strong> (instance: CodeMirror)</code></dt>
      <dd>Fires when the editor is scrolled.</dd>

      <dt id="event_refresh"><code><strong>"refresh"</strong> (instance: CodeMirror)</code></dt>
      <dd>Fires when the editor is <a href="#refresh">refreshed</a>
        or <a href="#setSize">resized</a>. Mostly useful to invalidate
        cached values that depend on the editor or character size.
      </dd>

      <dt id="event_optionChange"><code><strong>"optionChange"</strong> (instance: CodeMirror, option: string)</code>
      </dt>
      <dd>Dispatched every time an option is changed with <a href="#setOption"><code>setOption</code></a>.</dd>

      <dt id="event_scrollCursorIntoView"><code><strong>"scrollCursorIntoView"</strong> (instance: CodeMirror, event:
        Event)</code></dt>
      <dd>Fires when the editor tries to scroll its cursor into view.
        Can be hooked into to take care of additional scrollable
        containers around the editor. When the event object has
        its <code>preventDefault</code> method called, CodeMirror will
        not itself try to scroll the window.
      </dd>

      <dt id="event_update"><code><strong>"update"</strong> (instance: CodeMirror)</code></dt>
      <dd>Will be fired whenever CodeMirror updates its DOM display.</dd>

      <dt id="event_renderLine"><code><strong>"renderLine"</strong> (instance: CodeMirror, line: LineHandle, element:
        Element)</code></dt>
      <dd>Fired whenever a line is (re-)rendered to the DOM. Fired
        right after the DOM element is built, <em>before</em> it is
        added to the document. The handler may mess with the style of
        the resulting element, or add event handlers, but
        should <em>not</em> try to change the state of the editor.
      </dd>

      <dt id="event_dom"><code><strong>"mousedown"</strong>,
        <strong>"dblclick"</strong>, <strong>"touchstart"</strong>, <strong>"contextmenu"</strong>,
        <strong>"keydown"</strong>, <strong>"keypress"</strong>,
        <strong>"keyup"</strong>, <strong>"cut"</strong>, <strong>"copy"</strong>, <strong>"paste"</strong>,
        <strong>"dragstart"</strong>, <strong>"dragenter"</strong>,
        <strong>"dragover"</strong>, <strong>"dragleave"</strong>,
        <strong>"drop"</strong>
        (instance: CodeMirror, event: Event)</code></dt>
      <dd>Fired when CodeMirror is handling a DOM event of this type.
        You can <code>preventDefault</code> the event, or give it a
        truthy <code>codemirrorIgnore</code> property, to signal that
        CodeMirror should do no further handling.
      </dd>
    </dl>

    <p>Document objects (instances
      of <a href="#Doc"><code>CodeMirror.Doc</code></a>) emit the
      following events:</p>

    <dl>
      <dt id="event_doc_change"><code><strong>"change"</strong> (doc: CodeMirror.Doc, changeObj: object)</code></dt>
      <dd>Fired whenever a change occurs to the
        document. <code>changeObj</code> has a similar type as the
        object passed to the
        editor's <a href="#event_change"><code>"change"</code></a>
        event.
      </dd>

      <dt id="event_doc_beforeChange"><code><strong>"beforeChange"</strong> (doc: CodeMirror.Doc, change: object)</code>
      </dt>
      <dd>See the <a href="#event_beforeChange">description of the
        same event</a> on editor instances.
      </dd>

      <dt id="event_doc_cursorActivity"><code><strong>"cursorActivity"</strong> (doc: CodeMirror.Doc)</code></dt>
      <dd>Fired whenever the cursor or selection in this document
        changes.
      </dd>

      <dt id="event_doc_beforeSelectionChange"><code><strong>"beforeSelectionChange"</strong> (doc: CodeMirror.Doc,
        selection: {head, anchor})</code></dt>
      <dd>Equivalent to
        the <a href="#event_beforeSelectionChange">event by the same
          name</a> as fired on editor instances.
      </dd>
    </dl>

    <p>Line handles (as returned by, for
      example, <a href="#getLineHandle"><code>getLineHandle</code></a>)
      support these events:</p>

    <dl>
      <dt id="event_delete"><code><strong>"delete"</strong> ()</code></dt>
      <dd>Will be fired when the line object is deleted. A line object
        is associated with the <em>start</em> of the line. Mostly useful
        when you need to find out when your <a href="#setGutterMarker">gutter
          markers</a> on a given line are removed.
      </dd>
      <dt id="event_line_change"><code><strong>"change"</strong> (line: LineHandle, changeObj: object)</code></dt>
      <dd>Fires when the line's text content is changed in any way
        (but the line is not deleted outright). The <code>change</code>
        object is similar to the one passed
        to <a href="#event_change">change event</a> on the editor
        object.
      </dd>
    </dl>

    <p>Marked range handles (<code>CodeMirror.TextMarker</code>), as returned
      by <a href="#markText"><code>markText</code></a>
      and <a href="#setBookmark"><code>setBookmark</code></a>, emit the
      following events:</p>

    <dl>
      <dt id="event_beforeCursorEnter"><code><strong>"beforeCursorEnter"</strong> ()</code></dt>
      <dd>Fired when the cursor enters the marked range. From this
        event handler, the editor state may be inspected
        but <em>not</em> modified, with the exception that the range on
        which the event fires may be cleared.
      </dd>
      <dt id="event_clear"><code><strong>"clear"</strong> (from: {line, ch}, to: {line, ch})</code></dt>
      <dd>Fired when the range is cleared, either through cursor
        movement in combination
        with <a href="#mark_clearOnEnter"><code>clearOnEnter</code></a>
        or through a call to its <code>clear()</code> method. Will only
        be fired once per handle. Note that deleting the range through
        text editing does not fire this event, because an undo action
        might bring the range back into existence. <code>from</code>
        and <code>to</code> give the part of the document that the range
        spanned when it was cleared.
      </dd>
      <dt id="event_hide"><code><strong>"hide"</strong> ()</code></dt>
      <dd>Fired when the last part of the marker is removed from the
        document by editing operations.
      </dd>
      <dt id="event_unhide"><code><strong>"unhide"</strong> ()</code></dt>
      <dd>Fired when, after the marker was removed by editing, a undo
        operation brought the marker back.
      </dd>
    </dl>

    <p>Line widgets (<code>CodeMirror.LineWidget</code>), returned
      by <a href="#addLineWidget"><code>addLineWidget</code></a>, fire
      these events:</p>

    <dl>
      <dt id="event_redraw"><code><strong>"redraw"</strong> ()</code></dt>
      <dd>Fired whenever the editor re-adds the widget to the DOM.
        This will happen once right after the widget is added (if it is
        scrolled into view), and then again whenever it is scrolled out
        of view and back in again, or when changes to the editor options
        or the line the widget is on require the widget to be
        redrawn.
      </dd>
    </dl>
  </section>

  <section id=keymaps>
    <h2>Key Maps</h2>

    <p>Key maps are ways to associate keys and mouse buttons with
      functionality. A key map is an object mapping strings that
      identify the buttons to functions that implement their
      functionality.</p>

    <p>The CodeMirror distributions comes
      with <a href="../demo/emacs.html">Emacs</a>, <a href="../demo/vim.html">Vim</a>,
      and <a href="../demo/sublime.html">Sublime Text</a>-style keymaps.</p>

    <p>Keys are identified either by name or by character.
      The <code>CodeMirror.keyNames</code> object defines names for
      common keys and associates them with their key codes. Examples of
      names defined here are <code>Enter</code>, <code>F5</code>,
      and <code>Q</code>. These can be prefixed
      with <code>Shift-</code>, <code>Cmd-</code>, <code>Ctrl-</code>,
      and <code>Alt-</code> to specify a modifier. So for
      example, <code>Shift-Ctrl-Space</code> would be a valid key
      identifier.</p>

    <p>Common example: map the Tab key to insert spaces instead of a tab
      character.</p>

    <pre data-lang="javascript">
editor.setOption("extraKeys", {
  Tab: function(cm) {
    var spaces = Array(cm.getOption("indentUnit") + 1).join(" ");
    cm.replaceSelection(spaces);
  }
});</pre>

    <p>Alternatively, a character can be specified directly by
      surrounding it in single quotes, for example <code>'$'</code>
      or <code>'q'</code>. Due to limitations in the way browsers fire
      key events, these may not be prefixed with modifiers.</p>

    <p>To bind mouse buttons, use the names `LeftClick`,
      `MiddleClick`, and `RightClick`. These can also be prefixed with
      modifiers, and in addition, the word `Double` or `Triple` can be
      put before `Click` (as in `LeftDoubleClick`) to bind a double- or
      triple-click. The function for such a binding is passed the
      position that was clicked as second argument.</p>

    <p id="normalizeKeyMap">Multi-stroke key bindings can be specified
      by separating the key names by spaces in the property name, for
      example <code>Ctrl-X Ctrl-V</code>. When a map contains
      multi-stoke bindings or keys with modifiers that are not specified
      in the default order (<code>Shift-Cmd-Ctrl-Alt</code>), you must
      call <code>CodeMirror.normalizeKeyMap</code> on it before it can
      be used. This function takes a keymap and modifies it to normalize
      modifier order and properly recognize multi-stroke bindings. It
      will return the keymap itself.</p>

    <p>The <code>CodeMirror.keyMap</code> object associates key maps
      with names. User code and key map definitions can assign extra
      properties to this object. Anywhere where a key map is expected, a
      string can be given, which will be looked up in this object. It
      also contains the <code>"default"</code> key map holding the
      default bindings.</p>

    <p>The values of properties in key maps can be either functions of
      a single argument (the CodeMirror instance), strings, or
      <code>false</code>. Strings refer
      to <a href="#commands">commands</a>, which are described below. If
      the property is set to <code>false</code>, CodeMirror leaves
      handling of the key up to the browser. A key handler function may
      return <code>CodeMirror.Pass</code> to indicate that it has
      decided not to handle the key, and other handlers (or the default
      behavior) should be given a turn.</p>

    <p>Keys mapped to command names that start with the
      characters <code>"go"</code> or to functions that have a
      truthy <code>motion</code> property (which should be used for
      cursor-movement actions) will be fired even when an
      extra <code>Shift</code> modifier is present (i.e. <code>"Up":
        "goLineUp"</code> matches both up and shift-up). This is used to
      easily implement shift-selection.</p>

    <p>Key maps can defer to each other by defining
      a <code>fallthrough</code> property. This indicates that when a
      key is not found in the map itself, one or more other maps should
      be searched. It can hold either a single key map or an array of
      key maps.</p>

    <p>When a key map needs to set something up when it becomes
      active, or tear something down when deactivated, it can
      contain <code>attach</code> and/or <code>detach</code> properties,
      which should hold functions that take the editor instance and the
      next or previous keymap. Note that this only works for the
      <a href="#option_keyMap">top-level keymap</a>, not for fallthrough
      maps or maps added
      with <a href="#option_extraKeys"><code>extraKeys</code></a>
      or <a href="#addKeyMap"><code>addKeyMap</code></a>.</p>
  </section>

  <section id=commands>
    <h2>Commands</h2>

    <p>Commands are parameter-less actions that can be performed on an
      editor. Their main use is for key bindings. Commands are defined by
      adding properties to the <code>CodeMirror.commands</code> object.
      A number of common commands are defined by the library itself,
      most of them used by the default key bindings. The value of a
      command property must be a function of one argument (an editor
      instance).</p>

    <p>Some of the commands below are referenced in the default
      key map, but not defined by the core library. These are intended to
      be defined by user code or addons.</p>

    <p>Commands can also be run with
      the <a href="#execCommand"><code>execCommand</code></a>
      method.</p>

    <dl>
      <dt class=command id=command_selectAll><code><strong>selectAll</strong></code><span class=keybinding>Ctrl-A (PC), Cmd-A (Mac)</span>
      </dt>
      <dd>Select the whole content of the editor.</dd>

      <dt class=command id=command_singleSelection><code><strong>singleSelection</strong></code><span class=keybinding>Esc</span>
      </dt>
      <dd>When multiple selections are present, this deselects all but
        the primary selection.
      </dd>

      <dt class=command id=command_killLine><code><strong>killLine</strong></code><span
        class=keybinding>Ctrl-K (Mac)</span></dt>
      <dd>Emacs-style line killing. Deletes the part of the line after
        the cursor. If that consists only of whitespace, the newline at
        the end of the line is also deleted.
      </dd>

      <dt class=command id=command_deleteLine><code><strong>deleteLine</strong></code><span class=keybinding>Ctrl-D (PC), Cmd-D (Mac)</span>
      </dt>
      <dd>Deletes the whole line under the cursor, including newline at the end.</dd>

      <dt class=command id=command_delLineLeft><code><strong>delLineLeft</strong></code></dt>
      <dd>Delete the part of the line before the cursor.</dd>

      <dt class=command id=command_delWrappedLineLeft><code><strong>delWrappedLineLeft</strong></code><span
        class=keybinding>Cmd-Backspace (Mac)</span></dt>
      <dd>Delete the part of the line from the left side of the visual line the cursor is on to the cursor.</dd>

      <dt class=command id=command_delWrappedLineRight><code><strong>delWrappedLineRight</strong></code><span
        class=keybinding>Cmd-Delete (Mac)</span></dt>
      <dd>Delete the part of the line from the cursor to the right side of the visual line the cursor is on.</dd>

      <dt class=command id=command_undo><code><strong>undo</strong></code><span class=keybinding>Ctrl-Z (PC), Cmd-Z (Mac)</span>
      </dt>
      <dd>Undo the last change. Note that, because browsers still
        don't make it possible for scripts to react to or customize the
        context menu, selecting undo (or redo) from the context menu in
        a CodeMirror instance does not work.
      </dd>

      <dt class=command id=command_redo><code><strong>redo</strong></code><span class=keybinding>Ctrl-Y (PC), Shift-Cmd-Z (Mac), Cmd-Y (Mac)</span>
      </dt>
      <dd>Redo the last undone change.</dd>

      <dt class=command id=command_undoSelection><code><strong>undoSelection</strong></code><span class=keybinding>Ctrl-U (PC), Cmd-U (Mac)</span>
      </dt>
      <dd>Undo the last change to the selection, or if there are no
        selection-only changes at the top of the history, undo the last
        change.
      </dd>

      <dt class=command id=command_redoSelection><code><strong>redoSelection</strong></code><span class=keybinding>Alt-U (PC), Shift-Cmd-U (Mac)</span>
      </dt>
      <dd>Redo the last change to the selection, or the last text change if
        no selection changes remain.
      </dd>

      <dt class=command id=command_goDocStart><code><strong>goDocStart</strong></code><span class=keybinding>Ctrl-Home (PC), Cmd-Up (Mac), Cmd-Home (Mac)</span>
      </dt>
      <dd>Move the cursor to the start of the document.</dd>

      <dt class=command id=command_goDocEnd><code><strong>goDocEnd</strong></code><span class=keybinding>Ctrl-End (PC), Cmd-End (Mac), Cmd-Down (Mac)</span>
      </dt>
      <dd>Move the cursor to the end of the document.</dd>

      <dt class=command id=command_goLineStart><code><strong>goLineStart</strong></code><span class=keybinding>Alt-Left (PC), Ctrl-A (Mac)</span>
      </dt>
      <dd>Move the cursor to the start of the line.</dd>

      <dt class=command id=command_goLineStartSmart><code><strong>goLineStartSmart</strong></code><span
        class=keybinding>Home</span></dt>
      <dd>Move to the start of the text on the line, or if we are
        already there, to the actual start of the line (including
        whitespace).
      </dd>

      <dt class=command id=command_goLineEnd><code><strong>goLineEnd</strong></code><span class=keybinding>Alt-Right (PC), Ctrl-E (Mac)</span>
      </dt>
      <dd>Move the cursor to the end of the line.</dd>

      <dt class=command id=command_goLineRight><code><strong>goLineRight</strong></code><span class=keybinding>Cmd-Right (Mac)</span>
      </dt>
      <dd>Move the cursor to the right side of the visual line it is on.</dd>

      <dt class=command id=command_goLineLeft><code><strong>goLineLeft</strong></code><span class=keybinding>Cmd-Left (Mac)</span>
      </dt>
      <dd>Move the cursor to the left side of the visual line it is on. If
        this line is wrapped, that may not be the start of the line.
      </dd>

      <dt class=command id=command_goLineLeftSmart><code><strong>goLineLeftSmart</strong></code></dt>
      <dd>Move the cursor to the left side of the visual line it is
        on. If that takes it to the start of the line, behave
        like <a href="#command_goLineStartSmart"><code>goLineStartSmart</code></a>.
      </dd>

      <dt class=command id=command_goLineUp><code><strong>goLineUp</strong></code><span class=keybinding>Up, Ctrl-P (Mac)</span>
      </dt>
      <dd>Move the cursor up one line.</dd>

      <dt class=command id=command_goLineDown><code><strong>goLineDown</strong></code><span class=keybinding>Down, Ctrl-N (Mac)</span>
      </dt>
      <dd>Move down one line.</dd>

      <dt class=command id=command_goPageUp><code><strong>goPageUp</strong></code><span class=keybinding>PageUp, Shift-Ctrl-V (Mac)</span>
      </dt>
      <dd>Move the cursor up one screen, and scroll up by the same distance.</dd>

      <dt class=command id=command_goPageDown><code><strong>goPageDown</strong></code><span class=keybinding>PageDown, Ctrl-V (Mac)</span>
      </dt>
      <dd>Move the cursor down one screen, and scroll down by the same distance.</dd>

      <dt class=command id=command_goCharLeft><code><strong>goCharLeft</strong></code><span class=keybinding>Left, Ctrl-B (Mac)</span>
      </dt>
      <dd>Move the cursor one character left, going to the previous line
        when hitting the start of line.
      </dd>

      <dt class=command id=command_goCharRight><code><strong>goCharRight</strong></code><span class=keybinding>Right, Ctrl-F (Mac)</span>
      </dt>
      <dd>Move the cursor one character right, going to the next line
        when hitting the end of line.
      </dd>

      <dt class=command id=command_goColumnLeft><code><strong>goColumnLeft</strong></code></dt>
      <dd>Move the cursor one character left, but don't cross line boundaries.</dd>

      <dt class=command id=command_goColumnRight><code><strong>goColumnRight</strong></code></dt>
      <dd>Move the cursor one character right, don't cross line boundaries.</dd>

      <dt class=command id=command_goWordLeft><code><strong>goWordLeft</strong></code><span
        class=keybinding>Alt-B (Mac)</span></dt>
      <dd>Move the cursor to the start of the previous word.</dd>

      <dt class=command id=command_goWordRight><code><strong>goWordRight</strong></code><span class=keybinding>Alt-F (Mac)</span>
      </dt>
      <dd>Move the cursor to the end of the next word.</dd>

      <dt class=command id=command_goGroupLeft><code><strong>goGroupLeft</strong></code><span class=keybinding>Ctrl-Left (PC), Alt-Left (Mac)</span>
      </dt>
      <dd>Move to the left of the group before the cursor. A group is
        a stretch of word characters, a stretch of punctuation
        characters, a newline, or a stretch of <em>more than one</em>
        whitespace character.
      </dd>

      <dt class=command id=command_goGroupRight><code><strong>goGroupRight</strong></code><span class=keybinding>Ctrl-Right (PC), Alt-Right (Mac)</span>
      </dt>
      <dd>Move to the right of the group after the cursor
        (see <a href="#command_goGroupLeft">above</a>).
      </dd>

      <dt class=command id=command_delCharBefore><code><strong>delCharBefore</strong></code><span class=keybinding>Shift-Backspace, Ctrl-H (Mac)</span>
      </dt>
      <dd>Delete the character before the cursor.</dd>

      <dt class=command id=command_delCharAfter><code><strong>delCharAfter</strong></code><span class=keybinding>Delete, Ctrl-D (Mac)</span>
      </dt>
      <dd>Delete the character after the cursor.</dd>

      <dt class=command id=command_delWordBefore><code><strong>delWordBefore</strong></code><span class=keybinding>Alt-Backspace (Mac)</span>
      </dt>
      <dd>Delete up to the start of the word before the cursor.</dd>

      <dt class=command id=command_delWordAfter><code><strong>delWordAfter</strong></code><span class=keybinding>Alt-D (Mac)</span>
      </dt>
      <dd>Delete up to the end of the word after the cursor.</dd>

      <dt class=command id=command_delGroupBefore><code><strong>delGroupBefore</strong></code><span class=keybinding>Ctrl-Backspace (PC), Alt-Backspace (Mac)</span>
      </dt>
      <dd>Delete to the left of the <a href="#command_goGroupLeft">group</a> before the cursor.</dd>

      <dt class=command id=command_delGroupAfter><code><strong>delGroupAfter</strong></code><span class=keybinding>Ctrl-Delete (PC), Ctrl-Alt-Backspace (Mac), Alt-Delete (Mac)</span>
      </dt>
      <dd>Delete to the start of the <a href="#command_goGroupLeft">group</a> after the cursor.</dd>

      <dt class=command id=command_indentAuto><code><strong>indentAuto</strong></code><span
        class=keybinding>Shift-Tab</span></dt>
      <dd>Auto-indent the current line or selection.</dd>

      <dt class=command id=command_indentMore><code><strong>indentMore</strong></code><span class=keybinding>Ctrl-] (PC), Cmd-] (Mac)</span>
      </dt>
      <dd>Indent the current line or selection by one <a href="#option_indentUnit">indent unit</a>.</dd>

      <dt class=command id=command_indentLess><code><strong>indentLess</strong></code><span class=keybinding>Ctrl-[ (PC), Cmd-[ (Mac)</span>
      </dt>
      <dd>Dedent the current line or selection by one <a href="#option_indentUnit">indent unit</a>.</dd>

      <dt class=command id=command_insertTab><code><strong>insertTab</strong></code></dt>
      <dd>Insert a tab character at the cursor.</dd>

      <dt class=command id=command_insertSoftTab><code><strong>insertSoftTab</strong></code></dt>
      <dd>Insert the amount of spaces that match the width a tab at
        the cursor position would have.
      </dd>

      <dt class=command id=command_defaultTab><code><strong>defaultTab</strong></code><span class=keybinding>Tab</span>
      </dt>
      <dd>If something is selected, indent it by
        one <a href="#option_indentUnit">indent unit</a>. If nothing is
        selected, insert a tab character.
      </dd>

      <dt class=command id=command_transposeChars><code><strong>transposeChars</strong></code><span class=keybinding>Ctrl-T (Mac)</span>
      </dt>
      <dd>Swap the characters before and after the cursor.</dd>

      <dt class=command id=command_newlineAndIndent><code><strong>newlineAndIndent</strong></code><span
        class=keybinding>Enter</span></dt>
      <dd>Insert a newline and auto-indent the new line.</dd>

      <dt class=command id=command_toggleOverwrite><code><strong>toggleOverwrite</strong></code><span class=keybinding>Insert</span>
      </dt>
      <dd>Flip the <a href="#toggleOverwrite">overwrite</a> flag.</dd>

      <dt class=command id=command_save><code><strong>save</strong></code><span class=keybinding>Ctrl-S (PC), Cmd-S (Mac)</span>
      </dt>
      <dd>Not defined by the core library, only referred to in
        key maps. Intended to provide an easy way for user code to define
        a save command.
      </dd>

      <dt class=command id=command_find><code><strong>find</strong></code><span class=keybinding>Ctrl-F (PC), Cmd-F (Mac)</span>
      </dt>
      <dt class=command id=command_findNext><code><strong>findNext</strong></code><span class=keybinding>Ctrl-G (PC), Cmd-G (Mac)</span>
      </dt>
      <dt class=command id=command_findPrev><code><strong>findPrev</strong></code><span class=keybinding>Shift-Ctrl-G (PC), Shift-Cmd-G (Mac)</span>
      </dt>
      <dt class=command id=command_replace><code><strong>replace</strong></code><span class=keybinding>Shift-Ctrl-F (PC), Cmd-Alt-F (Mac)</span>
      </dt>
      <dt class=command id=command_replaceAll><code><strong>replaceAll</strong></code><span class=keybinding>Shift-Ctrl-R (PC), Shift-Cmd-Alt-F (Mac)</span>
      </dt>
      <dd>Not defined by the core library, but defined in
        the <a href="#addon_search">search addon</a> (or custom client
        addons).
      </dd>

    </dl>

  </section>

  <section id=styling>
    <h2>Customized Styling</h2>

    <p>Up to a certain extent, CodeMirror's look can be changed by
      modifying style sheet files. The style sheets supplied by modes
      simply provide the colors for that mode, and can be adapted in a
      very straightforward way. To style the editor itself, it is
      possible to alter or override the styles defined
      in <a href="../lib/codemirror.css"><code>codemirror.css</code></a>.</p>

    <p>Some care must be taken there, since a lot of the rules in this
      file are necessary to have CodeMirror function properly. Adjusting
      colors should be safe, of course, and with some care a lot of
      other things can be changed as well. The CSS classes defined in
      this file serve the following roles:</p>

    <dl>
      <dt id="class_CodeMirror"><code><strong>CodeMirror</strong></code></dt>
      <dd>The outer element of the editor. This should be used for the
        editor width, height, borders and positioning. Can also be used
        to set styles that should hold for everything inside the editor
        (such as font and font size), or to set a background. Setting
        this class' <code>height</code> style to <code>auto</code> will
        make the editor <a href="../demo/resize.html">resize to fit its
          content</a> (it is recommended to also set
        the <a href="#option_viewportMargin"><code>viewportMargin</code>
          option</a> to <code>Infinity</code> when doing this.
      </dd>

      <dt id="class_CodeMirror_focused"><code><strong>CodeMirror-focused</strong></code></dt>
      <dd>Whenever the editor is focused, the top element gets this
        class. This is used to hide the cursor and give the selection a
        different color when the editor is not focused.
      </dd>

      <dt id="class_CodeMirror_gutters"><code><strong>CodeMirror-gutters</strong></code></dt>
      <dd>This is the backdrop for all gutters. Use it to set the
        default gutter background color, and optionally add a border on
        the right of the gutters.
      </dd>

      <dt id="class_CodeMirror_linenumbers"><code><strong>CodeMirror-linenumbers</strong></code></dt>
      <dd>Use this for giving a background or width to the line number
        gutter.
      </dd>

      <dt id="class_CodeMirror_linenumber"><code><strong>CodeMirror-linenumber</strong></code></dt>
      <dd>Used to style the actual individual line numbers. These
        won't be children of the <code>CodeMirror-linenumbers</code>
        (plural) element, but rather will be absolutely positioned to
        overlay it. Use this to set alignment and text properties for
        the line numbers.
      </dd>

      <dt id="class_CodeMirror_lines"><code><strong>CodeMirror-lines</strong></code></dt>
      <dd>The visible lines. This is where you specify vertical
        padding for the editor content.
      </dd>

      <dt id="class_CodeMirror_cursor"><code><strong>CodeMirror-cursor</strong></code></dt>
      <dd>The cursor is a block element that is absolutely positioned.
        You can make it look whichever way you want.
      </dd>

      <dt id="class_CodeMirror_selected"><code><strong>CodeMirror-selected</strong></code></dt>
      <dd>The selection is represented by <code>span</code> elements
        with this class.
      </dd>

      <dt id="class_CodeMirror_matchingbracket"><code><strong>CodeMirror-matchingbracket</strong></code>,
        <code><strong>CodeMirror-nonmatchingbracket</strong></code></dt>
      <dd>These are used to style matched (or unmatched) brackets.</dd>
    </dl>

    <p>If your page's style sheets do funky things to
      all <code>div</code> or <code>pre</code> elements (you probably
      shouldn't do that), you'll have to define rules to cancel these
      effects out again for elements under the <code>CodeMirror</code>
      class.</p>

    <p>Themes are also simply CSS files, which define colors for
      various syntactic elements. See the files in
      the <a href="../theme"><code>theme</code></a> directory.</p>
  </section>

  <section id=api>
    <h2>Programming API</h2>

    <p>A lot of CodeMirror features are only available through its
      API. Thus, you need to write code (or
      use <a href="#addons">addons</a>) if you want to expose them to
      your users.</p>

    <p>Whenever points in the document are represented, the API uses
      objects with <code>line</code> and <code>ch</code> properties.
      Both are zero-based. CodeMirror makes sure to 'clip' any positions
      passed by client code so that they fit inside the document, so you
      shouldn't worry too much about sanitizing your coordinates. If you
      give <code>ch</code> a value of <code>null</code>, or don't
      specify it, it will be replaced with the length of the specified
      line. Such positions may also have a <code>sticky</code> property
      holding <code>"before"</code> or <code>"after"</code>, whether the
      position is associated with the character before or after it. This
      influences, for example, where the cursor is drawn on a
      line-break or bidi-direction boundary.</p>

    <p>Methods prefixed with <code>doc.</code> can, unless otherwise
      specified, be called both on <code>CodeMirror</code> (editor)
      instances and <code>CodeMirror.Doc</code> instances. Methods
      prefixed with <code>cm.</code> are <em>only</em> available
      on <code>CodeMirror</code> instances.</p>

    <h3 id="api_constructor">Constructor</h3>

    <p id="CodeMirror">Constructing an editor instance is done with
      the <code><strong>CodeMirror</strong>(place: Element|fn(Element),
        ?option: object)</code> constructor. If the <code>place</code>
      argument is a DOM element, the editor will be appended to it. If
      it is a function, it will be called, and is expected to place the
      editor into the document. <code>options</code> may be an element
      mapping <a href="#config">option names</a> to values. The options
      that it doesn't explicitly specify (or all options, if it is not
      passed) will be taken
      from <a href="#defaults"><code>CodeMirror.defaults</code></a>.</p>

    <p>Note that the options object passed to the constructor will be
      mutated when the instance's options
      are <a href="#setOption">changed</a>, so you shouldn't share such
      objects between instances.</p>

    <p>See <a href="#fromTextArea"><code>CodeMirror.fromTextArea</code></a>
      for another way to construct an editor instance.</p>

    <h3 id="api_content">Content manipulation methods</h3>

    <dl>
      <dt id="getValue"><code><strong>doc.getValue</strong>(?separator: string) → string</code></dt>
      <dd>Get the current editor content. You can pass it an optional
        argument to specify the string to be used to separate lines
        (defaults to <code>"\n"</code>).
      </dd>
      <dt id="setValue"><code><strong>doc.setValue</strong>(content: string)</code></dt>
      <dd>Set the editor content.</dd>

      <dt id="getRange"><code><strong>doc.getRange</strong>(from: {line, ch}, to: {line, ch}, ?separator: string) →
        string</code></dt>
      <dd>Get the text between the given points in the editor, which
        should be <code>{line, ch}</code> objects. An optional third
        argument can be given to indicate the line separator string to
        use (defaults to <code>"\n"</code>).
      </dd>
      <dt id="replaceRange"><code><strong>doc.replaceRange</strong>(replacement: string, from: {line, ch},
        to: {line, ch}, ?origin: string)</code></dt>
      <dd>Replace the part of the document between <code>from</code>
        and <code>to</code> with the given string. <code>from</code>
        and <code>to</code> must be <code>{line, ch}</code>
        objects. <code>to</code> can be left off to simply insert the
        string at position <code>from</code>. When <code>origin</code>
        is given, it will be passed on
        to <a href="#event_change"><code>"change"</code> events</a>, and
        its first letter will be used to determine whether this change
        can be merged with previous history events, in the way described
        for <a href="#selection_origin">selection origins</a>.
      </dd>

      <dt id="getLine"><code><strong>doc.getLine</strong>(n: integer) → string</code></dt>
      <dd>Get the content of line <code>n</code>.</dd>

      <dt id="lineCount"><code><strong>doc.lineCount</strong>() → integer</code></dt>
      <dd>Get the number of lines in the editor.</dd>
      <dt id="firstLine"><code><strong>doc.firstLine</strong>() → integer</code></dt>
      <dd>Get the first line of the editor. This will
        usually be zero but for <a href="#linkedDoc_from">linked sub-views</a>,
        or <a href="#api_doc">documents</a> instantiated with a non-zero
        first line, it might return other values.
      </dd>
      <dt id="lastLine"><code><strong>doc.lastLine</strong>() → integer</code></dt>
      <dd>Get the last line of the editor. This will
        usually be <code>doc.lineCount() - 1</code>,
        but for <a href="#linkedDoc_from">linked sub-views</a>,
        it might return other values.
      </dd>

      <dt id="getLineHandle"><code><strong>doc.getLineHandle</strong>(num: integer) → LineHandle</code></dt>
      <dd>Fetches the line handle for the given line number.</dd>
      <dt id="getLineNumber"><code><strong>doc.getLineNumber</strong>(handle: LineHandle) → integer</code></dt>
      <dd>Given a line handle, returns the current position of that
        line (or <code>null</code> when it is no longer in the
        document).
      </dd>
      <dt id="eachLine"><code><strong>doc.eachLine</strong>(f: (line: LineHandle))</code></dt>
      <dt><code><strong>doc.eachLine</strong>(start: integer, end: integer, f: (line: LineHandle))</code></dt>
      <dd>Iterate over the whole document, or if <code>start</code>
        and <code>end</code> line numbers are given, the range
        from <code>start</code> up to (not including) <code>end</code>,
        and call <code>f</code> for each line, passing the line handle.
        This is a faster way to visit a range of line handlers than
        calling <a href="#getLineHandle"><code>getLineHandle</code></a>
        for each of them. Note that line handles have
        a <code>text</code> property containing the line's content (as a
        string).
      </dd>

      <dt id="markClean"><code><strong>doc.markClean</strong>()</code></dt>
      <dd>Set the editor content as 'clean', a flag that it will
        retain until it is edited, and which will be set again when such
        an edit is undone again. Useful to track whether the content
        needs to be saved. This function is deprecated in favor
        of <a href="#changeGeneration"><code>changeGeneration</code></a>,
        which allows multiple subsystems to track different notions of
        cleanness without interfering.
      </dd>
      <dt id="changeGeneration"><code><strong>doc.changeGeneration</strong>(?closeEvent: boolean) → integer</code></dt>
      <dd>Returns a number that can later be passed
        to <a href="#isClean"><code>isClean</code></a> to test whether
        any edits were made (and not undone) in the meantime.
        If <code>closeEvent</code> is true, the current history event
        will be ‘closed’, meaning it can't be combined with further
        changes (rapid typing or deleting events are typically
        combined).
      </dd>
      <dt id="isClean"><code><strong>doc.isClean</strong>(?generation: integer) → boolean</code></dt>
      <dd>Returns whether the document is currently clean — not
        modified since initialization or the last call
        to <a href="#markClean"><code>markClean</code></a> if no
        argument is passed, or since the matching call
        to <a href="#changeGeneration"><code>changeGeneration</code></a>
        if a generation value is given.
      </dd>
    </dl>

    <h3 id="api_selection">Cursor and selection methods</h3>

    <dl>
      <dt id="getSelection"><code><strong>doc.getSelection</strong>(?lineSep: string) → string</code></dt>
      <dd>Get the currently selected code. Optionally pass a line
        separator to put between the lines in the output. When multiple
        selections are present, they are concatenated with instances
        of <code>lineSep</code> in between.
      </dd>
      <dt id="getSelections"><code><strong>doc.getSelections</strong>(?lineSep: string) → array&lt;string&gt;</code>
      </dt>
      <dd>Returns an array containing a string for each selection,
        representing the content of the selections.
      </dd>

      <dt id="replaceSelection"><code><strong>doc.replaceSelection</strong>(replacement: string, ?select: string)</code>
      </dt>
      <dd>Replace the selection(s) with the given string. By default,
        the new selection ends up after the inserted text. The
        optional <code>select</code> argument can be used to change
        this—passing <code>"around"</code> will cause the new text to be
        selected, passing <code>"start"</code> will collapse the
        selection to the start of the inserted text.
      </dd>
      <dt id="replaceSelections"><code><strong>doc.replaceSelections</strong>(replacements: array&lt;string&gt;,
        ?select: string)</code></dt>
      <dd>The length of the given array should be the same as the
        number of active selections. Replaces the content of the
        selections with the strings in the array.
        The <code>select</code> argument works the same as
        in <a href="#replaceSelection"><code>replaceSelection</code></a>.
      </dd>

      <dt id="getCursor"><code><strong>doc.getCursor</strong>(?start: string) → {line, ch}</code></dt>
      <dd>Retrieve one end of the <em>primary</em>
        selection. <code>start</code> is an optional string indicating
        which end of the selection to return. It may
        be <code>"from"</code>, <code>"to"</code>, <code>"head"</code>
        (the side of the selection that moves when you press
        shift+arrow), or <code>"anchor"</code> (the fixed side of the
        selection). Omitting the argument is the same as
        passing <code>"head"</code>. A <code>{line, ch}</code> object
        will be returned.
      </dd>
      <dt id="listSelections"><code><strong>doc.listSelections</strong>() → array&lt;{anchor, head}&gt;</code></dt>
      <dd>Retrieves a list of all current selections. These will
        always be sorted, and never overlap (overlapping selections are
        merged). Each object in the array contains <code>anchor</code>
        and <code>head</code> properties referring to <code>{line,
          ch}</code> objects.
      </dd>

      <dt id="somethingSelected"><code><strong>doc.somethingSelected</strong>() → boolean</code></dt>
      <dd>Return true if any text is selected.</dd>
      <dt id="setCursor"><code><strong>doc.setCursor</strong>(pos: {line, ch}|number, ?ch: number, ?options:
        object)</code></dt>
      <dd>Set the cursor position. You can either pass a
        single <code>{line, ch}</code> object, or the line and the
        character as two separate parameters. Will replace all
        selections with a single, empty selection at the given position.
        The supported options are the same as for <a href="#setSelection"><code>setSelection</code></a>.
      </dd>

      <dt id="setSelection"><code><strong>doc.setSelection</strong>(anchor: {line, ch}, ?head: {line, ch}, ?options:
        object)</code></dt>
      <dd>Set a single selection range. <code>anchor</code>
        and <code>head</code> should be <code>{line, ch}</code>
        objects. <code>head</code> defaults to <code>anchor</code> when
        not given. These options are supported:
        <dl>
          <dt id="selection_scroll"><code><strong>scroll</strong>: boolean</code></dt>
          <dd>Determines whether the selection head should be scrolled
            into view. Defaults to true.
          </dd>
          <dt id="selection_origin"><code><strong>origin</strong>: string</code></dt>
          <dd>Determines whether the selection history event may be
            merged with the previous one. When an origin starts with the
            character <code>+</code>, and the last recorded selection had
            the same origin and was similar (close
            in <a href="#option_historyEventDelay">time</a>, both
            collapsed or both non-collapsed), the new one will replace the
            old one. When it starts with <code>*</code>, it will always
            replace the previous event (if that had the same origin).
            Built-in motion uses the <code>"+move"</code> origin. User input uses the <code>"+input"</code> origin.
          </dd>
          <dt id="selection_bias"><code><strong>bias</strong>: number</code></dt>
          <dd>Determine the direction into which the selection endpoints
            should be adjusted when they fall inside
            an <a href="#mark_atomic">atomic</a> range. Can be either -1
            (backward) or 1 (forward). When not given, the bias will be
            based on the relative position of the old selection—the editor
            will try to move further away from that, to prevent getting
            stuck.
          </dd>
        </dl>
      </dd>

      <dt id="setSelections"><code><strong>doc.setSelections</strong>(ranges: array&lt;{anchor, head}&gt;, ?primary:
        integer, ?options: object)</code></dt>
      <dd>Sets a new set of selections. There must be at least one
        selection in the given array. When <code>primary</code> is a
        number, it determines which selection is the primary one. When
        it is not given, the primary index is taken from the previous
        selection, or set to the last range if the previous selection
        had less ranges than the new one. Supports the same options
        as <a href="#setSelection"><code>setSelection</code></a>.
      </dd>
      <dt id="addSelection"><code><strong>doc.addSelection</strong>(anchor: {line, ch}, ?head: {line, ch})</code></dt>
      <dd>Adds a new selection to the existing set of selections, and
        makes it the primary selection.
      </dd>

      <dt id="extendSelection"><code><strong>doc.extendSelection</strong>(from: {line, ch}, ?to: {line, ch}, ?options:
        object)</code></dt>
      <dd>Similar
        to <a href="#setSelection"><code>setSelection</code></a>, but
        will, if shift is held or
        the <a href="#setExtending">extending</a> flag is set, move the
        head of the selection while leaving the anchor at its current
        place. <code>to</code> is optional, and can be passed to ensure
        a region (for example a word or paragraph) will end up selected
        (in addition to whatever lies between that region and the
        current anchor). When multiple selections are present, all but
        the primary selection will be dropped by this method.
        Supports the same options as <a href="#setSelection"><code>setSelection</code></a>.
      </dd>
      <dt id="extendSelections"><code><strong>doc.extendSelections</strong>(heads: array&lt;{line, ch}&gt;, ?options:
        object)</code></dt>
      <dd>An equivalent
        of <a href="#extendSelection"><code>extendSelection</code></a>
        that acts on all selections at once.
      </dd>
      <dt id="extendSelectionsBy"><code><strong>doc.extendSelectionsBy</strong>(f: function(range: {anchor, head})
        → {line, ch}), ?options: object)</code></dt>
      <dd>Applies the given function to all existing selections, and
        calls <a href="#extendSelections"><code>extendSelections</code></a>
        on the result.
      </dd>
      <dt id="setExtending"><code><strong>doc.setExtending</strong>(value: boolean)</code></dt>
      <dd>Sets or clears the 'extending' flag, which acts similar to
        the shift key, in that it will cause cursor movement and calls
        to <a href="#extendSelection"><code>extendSelection</code></a>
        to leave the selection anchor in place.
      </dd>
      <dt id="getExtending"><code><strong>doc.getExtending</strong>() → boolean</code></dt>
      <dd>Get the value of the 'extending' flag.</dd>

      <dt id="hasFocus"><code><strong>cm.hasFocus</strong>() → boolean</code></dt>
      <dd>Tells you whether the editor currently has focus.</dd>

      <dt id="findPosH"><code><strong>cm.findPosH</strong>(start: {line, ch}, amount: integer, unit: string,
        visually: boolean) → {line, ch, ?hitSide: boolean}</code></dt>
      <dd>Used to find the target position for horizontal cursor
        motion. <code>start</code> is a <code>{line, ch}</code>
        object, <code>amount</code> an integer (may be negative),
        and <code>unit</code> one of the
        string <code>"char"</code>, <code>"column"</code>,
        or <code>"word"</code>. Will return a position that is produced
        by moving <code>amount</code> times the distance specified
        by <code>unit</code>. When <code>visually</code> is true, motion
        in right-to-left text will be visual rather than logical. When
        the motion was clipped by hitting the end or start of the
        document, the returned value will have a <code>hitSide</code>
        property set to true.
      </dd>
      <dt id="findPosV"><code><strong>cm.findPosV</strong>(start: {line, ch}, amount: integer, unit: string) → {line,
        ch, ?hitSide: boolean}</code></dt>
      <dd>Similar to <a href="#findPosH"><code>findPosH</code></a>,
        but used for vertical motion. <code>unit</code> may
        be <code>"line"</code> or <code>"page"</code>. The other
        arguments and the returned value have the same interpretation as
        they have in <code>findPosH</code>.
      </dd>

      <dt id="findWordAt"><code><strong>cm.findWordAt</strong>(pos: {line, ch}) → {anchor: {line, ch}, head: {line, ch}}</code>
      </dt>
      <dd>Returns the start and end of the 'word' (the stretch of
        letters, whitespace, or punctuation) at the given position.
      </dd>
    </dl>

    <h3 id="api_configuration">Configuration methods</h3>

    <dl>
      <dt id="setOption"><code><strong>cm.setOption</strong>(option: string, value: any)</code></dt>
      <dd>Change the configuration of the editor. <code>option</code>
        should the name of an <a href="#config">option</a>,
        and <code>value</code> should be a valid value for that
        option.
      </dd>
      <dt id="getOption"><code><strong>cm.getOption</strong>(option: string) → any</code></dt>
      <dd>Retrieves the current value of the given option for this
        editor instance.
      </dd>

      <dt id="addKeyMap"><code><strong>cm.addKeyMap</strong>(map: object, bottom: boolean)</code></dt>
      <dd>Attach an additional <a href="#keymaps">key map</a> to the
        editor. This is mostly useful for addons that need to register
        some key handlers without trampling on
        the <a href="#option_extraKeys"><code>extraKeys</code></a>
        option. Maps added in this way have a higher precedence than
        the <code>extraKeys</code>
        and <a href="#option_keyMap"><code>keyMap</code></a> options,
        and between them, the maps added earlier have a lower precedence
        than those added later, unless the <code>bottom</code> argument
        was passed, in which case they end up below other key maps added
        with this method.
      </dd>
      <dt id="removeKeyMap"><code><strong>cm.removeKeyMap</strong>(map: object)</code></dt>
      <dd>Disable a keymap added
        with <a href="#addKeyMap"><code>addKeyMap</code></a>. Either
        pass in the key map object itself, or a string, which will be
        compared against the <code>name</code> property of the active
        key maps.
      </dd>

      <dt id="addOverlay"><code><strong>cm.addOverlay</strong>(mode: string|object, ?options: object)</code></dt>
      <dd>Enable a highlighting overlay. This is a stateless mini-mode
        that can be used to add extra highlighting. For example,
        the <a href="../demo/search.html">search addon</a> uses it to
        highlight the term that's currently being
        searched. <code>mode</code> can be a <a href="#option_mode">mode
          spec</a> or a mode object (an object with
        a <a href="#token"><code>token</code></a> method).
        The <code>options</code> parameter is optional. If given, it
        should be an object, optionally containing the following options:
        <dl>
          <dt><code><strong>opaque</strong>: bool</code></dt>
          <dd>Defaults to off, but can be given to allow the overlay
            styling, when not <code>null</code>, to override the styling of
            the base mode entirely, instead of the two being applied
            together.
          </dd>
          <dt><code><strong>priority</strong>: number</code></dt>
          <dd>Determines the ordering in which the overlays are
            applied. Those with high priority are applied after those
            with lower priority, and able to override the opaqueness of
            the ones that come before. Defaults to 0.
          </dd>
        </dl>
      </dd>

      <dt id="removeOverlay"><code><strong>cm.removeOverlay</strong>(mode: string|object)</code></dt>
      <dd>Pass this the exact value passed for the <code>mode</code>
        parameter to <a href="#addOverlay"><code>addOverlay</code></a>,
        or a string that corresponds to the <code>name</code> property of
        that value, to remove an overlay again.
      </dd>

      <dt id="on"><code><strong>cm.on</strong>(type: string, func: (...args))</code></dt>
      <dd>Register an event handler for the given event type (a
        string) on the editor instance. There is also
        a <code>CodeMirror.on(object, type, func)</code> version
        that allows registering of events on any object.
      </dd>
      <dt id="off"><code><strong>cm.off</strong>(type: string, func: (...args))</code></dt>
      <dd>Remove an event handler on the editor instance. An
        equivalent <code>CodeMirror.off(object, type,
          func)</code> also exists.
      </dd>
    </dl>

    <h3 id="api_doc">Document management methods</h3>

    <p id="Doc">Each editor is associated with an instance
      of <code>CodeMirror.Doc</code>, its document. A document
      represents the editor content, plus a selection, an undo history,
      and a <a href="#option_mode">mode</a>. A document can only be
      associated with a single editor at a time. You can create new
      documents by calling the <code>CodeMirror.Doc(text, mode,
        firstLineNumber)</code> constructor. The last two arguments are
      optional and can be used to set a mode for the document and make
      it start at a line number other than 0, respectively.</p>

    <dl>
      <dt id="getDoc"><code><strong>cm.getDoc</strong>() → Doc</code></dt>
      <dd>Retrieve the currently active document from an editor.</dd>
      <dt id="getEditor"><code><strong>doc.getEditor</strong>() → CodeMirror</code></dt>
      <dd>Retrieve the editor associated with a document. May
        return <code>null</code>.
      </dd>

      <dt id="swapDoc"><code><strong>cm.swapDoc</strong>(doc: CodeMirror.Doc) → Doc</code></dt>
      <dd>Attach a new document to the editor. Returns the old
        document, which is now no longer associated with an editor.
      </dd>

      <dt id="copy"><code><strong>doc.copy</strong>(copyHistory: boolean) → Doc</code></dt>
      <dd>Create an identical copy of the given doc.
        When <code>copyHistory</code> is true, the history will also be
        copied. Can not be called directly on an editor.
      </dd>

      <dt id="linkedDoc"><code><strong>doc.linkedDoc</strong>(options: object) → Doc</code></dt>
      <dd>Create a new document that's linked to the target document.
        Linked documents will stay in sync (changes to one are also
        applied to the other) until <a href="#unlinkDoc">unlinked</a>.
        These are the options that are supported:
        <dl>
          <dt id="linkedDoc_sharedHist"><code><strong>sharedHist</strong>: boolean</code></dt>
          <dd>When turned on, the linked copy will share an undo
            history with the original. Thus, something done in one of
            the two can be undone in the other, and vice versa.
          </dd>
          <dt id="linkedDoc_from"><code><strong>from</strong>: integer</code></dt>
          <dt id="linkedDoc_to"><code><strong>to</strong>: integer</code></dt>
          <dd>Can be given to make the new document a subview of the
            original. Subviews only show a given range of lines. Note
            that line coordinates inside the subview will be consistent
            with those of the parent, so that for example a subview
            starting at line 10 will refer to its first line as line 10,
            not 0.
          </dd>
          <dt id="linkedDoc_mode"><code><strong>mode</strong>: string|object</code></dt>
          <dd>By default, the new document inherits the mode of the
            parent. This option can be set to
            a <a href="#option_mode">mode spec</a> to give it a
            different mode.
          </dd>
        </dl>
      </dd>
      <dt id="unlinkDoc"><code><strong>doc.unlinkDoc</strong>(doc: CodeMirror.Doc)</code></dt>
      <dd>Break the link between two documents. After calling this,
        changes will no longer propagate between the documents, and, if
        they had a shared history, the history will become
        separate.
      </dd>
      <dt id="iterLinkedDocs"><code><strong>doc.iterLinkedDocs</strong>(function: (doc: CodeMirror.Doc, sharedHist:
        boolean))</code></dt>
      <dd>Will call the given function for all documents linked to the
        target document. It will be passed two arguments, the linked document
        and a boolean indicating whether that document shares history
        with the target.
      </dd>
    </dl>

    <h3 id="api_history">History-related methods</h3>

    <dl>
      <dt id="undo"><code><strong>doc.undo</strong>()</code></dt>
      <dd>Undo one edit (if any undo events are stored).</dd>
      <dt id="redo"><code><strong>doc.redo</strong>()</code></dt>
      <dd>Redo one undone edit.</dd>

      <dt id="undoSelection"><code><strong>doc.undoSelection</strong>()</code></dt>
      <dd>Undo one edit or selection change.</dd>
      <dt id="redoSelection"><code><strong>doc.redoSelection</strong>()</code></dt>
      <dd>Redo one undone edit or selection change.</dd>

      <dt id="historySize"><code><strong>doc.historySize</strong>() → {undo: integer, redo: integer}</code></dt>
      <dd>Returns an object with <code>{undo, redo}</code> properties,
        both of which hold integers, indicating the amount of stored
        undo and redo operations.
      </dd>
      <dt id="clearHistory"><code><strong>doc.clearHistory</strong>()</code></dt>
      <dd>Clears the editor's undo history.</dd>
      <dt id="getHistory"><code><strong>doc.getHistory</strong>() → object</code></dt>
      <dd>Get a (JSON-serializable) representation of the undo history.</dd>
      <dt id="setHistory"><code><strong>doc.setHistory</strong>(history: object)</code></dt>
      <dd>Replace the editor's undo history with the one provided,
        which must be a value as returned
        by <a href="#getHistory"><code>getHistory</code></a>. Note that
        this will have entirely undefined results if the editor content
        isn't also the same as it was when <code>getHistory</code> was
        called.
      </dd>
    </dl>

    <h3 id="api_marker">Text-marking methods</h3>

    <dl>
      <dt id="markText"><code><strong>doc.markText</strong>(from: {line, ch}, to: {line, ch}, ?options: object) →
        TextMarker</code></dt>
      <dd>Can be used to mark a range of text with a specific CSS
        class name. <code>from</code> and <code>to</code> should
        be <code>{line, ch}</code> objects. The <code>options</code>
        parameter is optional. When given, it should be an object that
        may contain the following configuration options:
        <dl>
          <dt id="mark_className"><code><strong>className</strong>: string</code></dt>
          <dd>Assigns a CSS class to the marked stretch of text.</dd>
          <dt id="mark_inclusiveLeft"><code><strong>inclusiveLeft</strong>: boolean</code></dt>
          <dd>Determines whether
            text inserted on the left of the marker will end up inside
            or outside of it.
          </dd>
          <dt id="mark_inclusiveRight"><code><strong>inclusiveRight</strong>: boolean</code></dt>
          <dd>Like <code>inclusiveLeft</code>,
            but for the right side.
          </dd>
          <dt id="mark_atomic"><code><strong>atomic</strong>: boolean</code></dt>
          <dd>Atomic ranges act as a single unit when cursor movement is
            concerned—i.e. it is impossible to place the cursor inside of
            them. In atomic ranges, <code>inclusiveLeft</code>
            and <code>inclusiveRight</code> have a different meaning—they
            will prevent the cursor from being placed respectively
            directly before and directly after the range.
          </dd>
          <dt id="mark_collapsed"><code><strong>collapsed</strong>: boolean</code></dt>
          <dd>Collapsed ranges do not show up in the display. Setting a
            range to be collapsed will automatically make it atomic.
          </dd>
          <dt id="mark_clearOnEnter"><code><strong>clearOnEnter</strong>: boolean</code></dt>
          <dd>When enabled, will cause the mark to clear itself whenever
            the cursor enters its range. This is mostly useful for
            text-replacement widgets that need to 'snap open' when the
            user tries to edit them. The
            <a href="#event_clear"><code>"clear"</code></a> event
            fired on the range handle can be used to be notified when this
            happens.
          </dd>
          <dt id="mark_clearWhenEmpty"><code><strong>clearWhenEmpty</strong>: boolean</code></dt>
          <dd>Determines whether the mark is automatically cleared when
            it becomes empty. Default is true.
          </dd>
          <dt id="mark_replacedWith"><code><strong>replacedWith</strong>: Element</code></dt>
          <dd>Use a given node to display this range. Implies both
            collapsed and atomic. The given DOM node <em>must</em> be an
            inline element (as opposed to a block element).
          </dd>
          <dt><code><strong>handleMouseEvents</strong>: boolean</code></dt>
          <dd>When <code>replacedWith</code> is given, this determines
            whether the editor will capture mouse and drag events
            occurring in this widget. Default is false—the events will be
            left alone for the default browser handler, or specific
            handlers on the widget, to capture.
          </dd>
          <dt id="mark_readOnly"><code><strong>readOnly</strong>: boolean</code></dt>
          <dd>A read-only span can, as long as it is not cleared, not be
            modified except by
            calling <a href="#setValue"><code>setValue</code></a> to reset
            the whole document. <em>Note:</em> adding a read-only span
            currently clears the undo history of the editor, because
            existing undo events being partially nullified by read-only
            spans would corrupt the history (in the current
            implementation).
          </dd>
          <dt id="mark_addToHistory"><code><strong>addToHistory</strong>: boolean</code></dt>
          <dd>When set to true (default is false), adding this marker
            will create an event in the undo history that can be
            individually undone (clearing the marker).
          </dd>
          <dt id="mark_startStyle"><code><strong>startStyle</strong>: string</code></dt>
          <dd>Can be used to specify
            an extra CSS class to be applied to the leftmost span that
            is part of the marker.
          </dd>
          <dt id="mark_endStyle"><code><strong>endStyle</strong>: string</code></dt>
          <dd>Equivalent
            to <code>startStyle</code>, but for the rightmost span.
          </dd>
          <dt id="mark_css"><code><strong>css</strong>: string</code></dt>
          <dd>A string of CSS to be applied to the covered text. For example <code>"color: #fe3"</code>.</dd>
          <dt id="mark_title"><code><strong>title</strong>:
            string</code></dt>
          <dd>When given, will give the nodes created
            for this span a HTML <code>title</code> attribute with the
            given value.
          </dd>
          <dt id="mark_shared"><code><strong>shared</strong>: boolean</code></dt>
          <dd>When the
            target document is <a href="#linkedDoc">linked</a> to other
            documents, you can set <code>shared</code> to true to make the
            marker appear in all documents. By default, a marker appears
            only in its target document.
          </dd>
        </dl>
        The method will return an object that represents the marker
        (with constructor <code>CodeMirror.TextMarker</code>), which
        exposes three methods:
        <code><strong>clear</strong>()</code>, to remove the mark,
        <code><strong>find</strong>()</code>, which returns
        a <code>{from, to}</code> object (both holding document
        positions), indicating the current position of the marked range,
        or <code>undefined</code> if the marker is no longer in the
        document, and finally <code><strong>changed</strong>()</code>,
        which you can call if you've done something that might change
        the size of the marker (for example changing the content of
        a <a href="#mark_replacedWith"><code>replacedWith</code></a>
        node), and want to cheaply update the display.
      </dd>

      <dt id="setBookmark"><code><strong>doc.setBookmark</strong>(pos: {line, ch}, ?options: object) → TextMarker</code>
      </dt>
      <dd>Inserts a bookmark, a handle that follows the text around it
        as it is being edited, at the given position. A bookmark has two
        methods <code>find()</code> and <code>clear()</code>. The first
        returns the current position of the bookmark, if it is still in
        the document, and the second explicitly removes the bookmark.
        The options argument is optional. If given, the following
        properties are recognized:
        <dl>
          <dt><code><strong>widget</strong>: Element</code></dt>
          <dd>Can be used to display a DOM
            node at the current location of the bookmark (analogous to
            the <a href="#mark_replacedWith"><code>replacedWith</code></a>
            option to <a href="#markText"><code>markText</code></a>).
          </dd>
          <dt><code><strong>insertLeft</strong>: boolean</code></dt>
          <dd>By default, text typed
            when the cursor is on top of the bookmark will end up to the
            right of the bookmark. Set this option to true to make it go
            to the left instead.
          </dd>
          <dt><code><strong>shared</strong>: boolean</code></dt>
          <dd>See
            the corresponding <a href="#mark_shared">option</a>
            to <code>markText</code>.
          </dd>
          <dt><code><strong>handleMouseEvents</strong>: boolean</code></dt>
          <dd>As with <a href="#markText"><code>markText</code></a>,
            this determines whether mouse events on the widget inserted
            for this bookmark are handled by CodeMirror. The default is
            false.
          </dd>
        </dl>
      </dd>

      <dt id="findMarks"><code><strong>doc.findMarks</strong>(from: {line, ch}, to: {line, ch}) → array&lt;TextMarker&gt;</code>
      </dt>
      <dd>Returns an array of all the bookmarks and marked ranges
        found between the given positions (non-inclusive).
      </dd>
      <dt id="findMarksAt"><code><strong>doc.findMarksAt</strong>(pos: {line, ch}) → array&lt;TextMarker&gt;</code></dt>
      <dd>Returns an array of all the bookmarks and marked ranges
        present at the given position.
      </dd>
      <dt id="getAllMarks"><code><strong>doc.getAllMarks</strong>() → array&lt;TextMarker&gt;</code></dt>
      <dd>Returns an array containing all marked ranges in the document.</dd>
    </dl>

    <h3 id="api_decoration">Widget, gutter, and decoration methods</h3>

    <dl>
      <dt id="setGutterMarker"><code><strong>doc.setGutterMarker</strong>(line: integer|LineHandle, gutterID: string,
        value: Element) → LineHandle</code></dt>
      <dd>Sets the gutter marker for the given gutter (identified by
        its CSS class, see
        the <a href="#option_gutters"><code>gutters</code></a> option)
        to the given value. Value can be either <code>null</code>, to
        clear the marker, or a DOM element, to set it. The DOM element
        will be shown in the specified gutter next to the specified
        line.
      </dd>

      <dt id="clearGutter"><code><strong>doc.clearGutter</strong>(gutterID: string)</code></dt>
      <dd>Remove all gutter markers in
        the <a href="#option_gutters">gutter</a> with the given ID.
      </dd>

      <dt id="addLineClass"><code><strong>doc.addLineClass</strong>(line: integer|LineHandle, where: string, class:
        string) → LineHandle</code></dt>
      <dd>Set a CSS class name for the given line. <code>line</code>
        can be a number or a line handle. <code>where</code> determines
        to which element this class should be applied, can can be one
        of <code>"text"</code> (the text element, which lies in front of
        the selection), <code>"background"</code> (a background element
        that will be behind the selection), <code>"gutter"</code> (the
        line's gutter space), or <code>"wrap"</code> (the wrapper node
        that wraps all of the line's elements, including gutter
        elements). <code>class</code> should be the name of the class to
        apply.
      </dd>

      <dt id="removeLineClass"><code><strong>doc.removeLineClass</strong>(line: integer|LineHandle, where: string,
        class: string) → LineHandle</code></dt>
      <dd>Remove a CSS class from a line. <code>line</code> can be a
        line handle or number. <code>where</code> should be one
        of <code>"text"</code>, <code>"background"</code>,
        or <code>"wrap"</code>
        (see <a href="#addLineClass"><code>addLineClass</code></a>). <code>class</code>
        can be left off to remove all classes for the specified node, or
        be a string to remove only a specific class.
      </dd>

      <dt id="lineInfo"><code><strong>doc.lineInfo</strong>(line: integer|LineHandle) → object</code></dt>
      <dd>Returns the line number, text content, and marker status of
        the given line, which can be either a number or a line handle.
        The returned object has the structure <code>{line, handle, text,
          gutterMarkers, textClass, bgClass, wrapClass, widgets}</code>,
        where <code>gutterMarkers</code> is an object mapping gutter IDs
        to marker elements, and <code>widgets</code> is an array
        of <a href="#addLineWidget">line widgets</a> attached to this
        line, and the various class properties refer to classes added
        with <a href="#addLineClass"><code>addLineClass</code></a>.
      </dd>

      <dt id="addWidget"><code><strong>cm.addWidget</strong>(pos: {line, ch}, node: Element, scrollIntoView:
        boolean)</code></dt>
      <dd>Puts <code>node</code>, which should be an absolutely
        positioned DOM node, into the editor, positioned right below the
        given <code>{line, ch}</code> position.
        When <code>scrollIntoView</code> is true, the editor will ensure
        that the entire node is visible (if possible). To remove the
        widget again, simply use DOM methods (move it somewhere else, or
        call <code>removeChild</code> on its parent).
      </dd>

      <dt id="addLineWidget"><code><strong>doc.addLineWidget</strong>(line: integer|LineHandle, node: Element, ?options:
        object) → LineWidget</code></dt>
      <dd>Adds a line widget, an element shown below a line, spanning
        the whole of the editor's width, and moving the lines below it
        downwards. <code>line</code> should be either an integer or a
        line handle, and <code>node</code> should be a DOM node, which
        will be displayed below the given line. <code>options</code>,
        when given, should be an object that configures the behavior of
        the widget. The following options are supported (all default to
        false):
        <dl>
          <dt><code><strong>coverGutter</strong>: boolean</code></dt>
          <dd>Whether the widget should cover the gutter.</dd>
          <dt><code><strong>noHScroll</strong>: boolean</code></dt>
          <dd>Whether the widget should stay fixed in the face of
            horizontal scrolling.
          </dd>
          <dt><code><strong>above</strong>: boolean</code></dt>
          <dd>Causes the widget to be placed above instead of below
            the text of the line.
          </dd>
          <dt><code><strong>handleMouseEvents</strong>: boolean</code></dt>
          <dd>Determines whether the editor will capture mouse and
            drag events occurring in this widget. Default is false—the
            events will be left alone for the default browser handler,
            or specific handlers on the widget, to capture.
          </dd>
          <dt><code><strong>insertAt</strong>: integer</code></dt>
          <dd>By default, the widget is added below other widgets for
            the line. This option can be used to place it at a different
            position (zero for the top, N to put it after the Nth other
            widget). Note that this only has effect once, when the
            widget is created.
        </dl>
        Note that the widget node will become a descendant of nodes with
        CodeMirror-specific CSS classes, and those classes might in some
        cases affect it. This method returns an object that represents
        the widget placement. It'll have a <code>line</code> property
        pointing at the line handle that it is associated with, and the following methods:
        <dl>
          <dt id="widget_clear"><code><strong>clear</strong>()</code></dt>
          <dd>Removes the widget.</dd>
          <dt id="widget_changed"><code><strong>changed</strong>()</code></dt>
          <dd>Call
            this if you made some change to the widget's DOM node that
            might affect its height. It'll force CodeMirror to update
            the height of the line that contains the widget.
          </dd>
        </dl>
      </dd>
    </dl>

    <h3 id="api_sizing">Sizing, scrolling and positioning methods</h3>

    <dl>
      <dt id="setSize"><code><strong>cm.setSize</strong>(width: number|string, height: number|string)</code></dt>
      <dd>Programmatically set the size of the editor (overriding the
        applicable <a href="#css-resize">CSS
          rules</a>). <code>width</code> and <code>height</code>
        can be either numbers (interpreted as pixels) or CSS units
        (<code>"100%"</code>, for example). You can
        pass <code>null</code> for either of them to indicate that that
        dimension should not be changed.
      </dd>

      <dt id="scrollTo"><code><strong>cm.scrollTo</strong>(x: number, y: number)</code></dt>
      <dd>Scroll the editor to a given (pixel) position. Both
        arguments may be left as <code>null</code>
        or <code>undefined</code> to have no effect.
      </dd>
      <dt id="getScrollInfo"><code><strong>cm.getScrollInfo</strong>() → {left, top, width, height, clientWidth,
        clientHeight}</code></dt>
      <dd>Get an <code>{left, top, width, height, clientWidth,
        clientHeight}</code> object that represents the current scroll
        position, the size of the scrollable area, and the size of the
        visible area (minus scrollbars).
      </dd>
      <dt id="scrollIntoView"><code><strong>cm.scrollIntoView</strong>(what: {line, ch}|{left, top, right,
        bottom}|{from, to}|null, ?margin: number)</code></dt>
      <dd>Scrolls the given position into view. <code>what</code> may
        be <code>null</code> to scroll the cursor into view,
        a <code>{line, ch}</code> position to scroll a character into
        view, a <code>{left, top, right, bottom}</code> pixel range (in
        editor-local coordinates), or a range <code>{from, to}</code>
        containing either two character positions or two pixel squares.
        The <code>margin</code> parameter is optional. When given, it
        indicates the amount of vertical pixels around the given area
        that should be made visible as well.
      </dd>

      <dt id="cursorCoords"><code><strong>cm.cursorCoords</strong>(where: boolean|{line, ch}, mode: string) → {left,
        top, bottom}</code></dt>
      <dd>Returns an <code>{left, top, bottom}</code> object
        containing the coordinates of the cursor position.
        If <code>mode</code> is <code>"local"</code>, they will be
        relative to the top-left corner of the editable document. If it
        is <code>"page"</code> or not given, they are relative to the
        top-left corner of the page. If <code>mode</code>
        is <code>"window"</code>, the coordinates are relative to the
        top-left corner of the currently visible (scrolled)
        window. <code>where</code> can be a boolean indicating whether
        you want the start (<code>true</code>) or the end
        (<code>false</code>) of the selection, or, if a <code>{line,
          ch}</code> object is given, it specifies the precise position at
        which you want to measure.
      </dd>
      <dt id="charCoords"><code><strong>cm.charCoords</strong>(pos: {line, ch}, ?mode: string) → {left, right, top,
        bottom}</code></dt>
      <dd>Returns the position and dimensions of an arbitrary
        character. <code>pos</code> should be a <code>{line, ch}</code>
        object. This differs from <code>cursorCoords</code> in that
        it'll give the size of the whole character, rather than just the
        position that the cursor would have when it would sit at that
        position.
      </dd>
      <dt id="coordsChar"><code><strong>cm.coordsChar</strong>(object: {left, top}, ?mode: string) → {line, ch}</code>
      </dt>
      <dd>Given an <code>{left, top}</code> object (e.g. coordinates of a mouse event) returns
        the <code>{line, ch}</code> position that corresponds to it. The
        optional <code>mode</code> parameter determines relative to what
        the coordinates are interpreted. It may
        be <code>"window"</code>, <code>"page"</code> (the default),
        or <code>"local"</code>.
      </dd>
      <dt id="lineAtHeight"><code><strong>cm.lineAtHeight</strong>(height: number, ?mode: string) → number</code></dt>
      <dd>Computes the line at the given pixel
        height. <code>mode</code> can be one of the same strings
        that <a href="#coordsChar"><code>coordsChar</code></a>
        accepts.
      </dd>
      <dt id="heightAtLine"><code><strong>cm.heightAtLine</strong>(line: integer|LineHandle, ?mode: string,
        ?includeWidgets: bool) → number</code></dt>
      <dd>Computes the height of the top of a line, in the coordinate
        system specified by <code>mode</code>
        (see <a href="#coordsChar"><code>coordsChar</code></a>), which
        defaults to <code>"page"</code>. When a line below the bottom of
        the document is specified, the returned value is the bottom of
        the last line in the document. By default, the position of the
        actual text is returned. If `includeWidgets` is true and the
        line has line widgets, the position above the first line widget
        is returned.
      </dd>
      <dt id="defaultTextHeight"><code><strong>cm.defaultTextHeight</strong>() → number</code></dt>
      <dd>Returns the line height of the default font for the editor.</dd>
      <dt id="defaultCharWidth"><code><strong>cm.defaultCharWidth</strong>() → number</code></dt>
      <dd>Returns the pixel width of an 'x' in the default font for
        the editor. (Note that for non-monospace fonts, this is mostly
        useless, and even for monospace fonts, non-ascii characters
        might have a different width).
      </dd>

      <dt id="getViewport"><code><strong>cm.getViewport</strong>() → {from: number, to: number}</code></dt>
      <dd>Returns a <code>{from, to}</code> object indicating the
        start (inclusive) and end (exclusive) of the currently rendered
        part of the document. In big documents, when most content is
        scrolled out of view, CodeMirror will only render the visible
        part, and a margin around it. See also
        the <a href="#event_viewportChange"><code>viewportChange</code></a>
        event.
      </dd>

      <dt id="refresh"><code><strong>cm.refresh</strong>()</code></dt>
      <dd>If your code does something to change the size of the editor
        element (window resizes are already listened for), or unhides
        it, you should probably follow up by calling this method to
        ensure CodeMirror is still looking as intended. See also
        the <a href="#addon_autorefresh">autorefresh addon</a>.
      </dd>
    </dl>

    <h3 id="api_mode">Mode, state, and token-related methods</h3>

    <p>When writing language-aware functionality, it can often be
      useful to hook into the knowledge that the CodeMirror language
      mode has. See <a href="#modeapi">the section on modes</a> for a
      more detailed description of how these work.</p>

    <dl>
      <dt id="getMode"><code><strong>doc.getMode</strong>() → object</code></dt>
      <dd>Gets the (outer) mode object for the editor. Note that this
        is distinct from <code>getOption("mode")</code>, which gives you
        the mode specification, rather than the resolved, instantiated
        <a href="#defineMode">mode object</a>.
      </dd>

      <dt id="getModeAt"><code><strong>cm.getModeAt</strong>(pos: {line, ch}) → object</code></dt>
      <dd>Gets the inner mode at a given position. This will return
        the same as <a href="#getMode"><code>getMode</code></a> for
        simple modes, but will return an inner mode for nesting modes
        (such as <code>htmlmixed</code>).
      </dd>

      <dt id="getTokenAt"><code><strong>cm.getTokenAt</strong>(pos: {line, ch}, ?precise: boolean) → object</code></dt>
      <dd>Retrieves information about the token the current mode found
        before the given position (a <code>{line, ch}</code> object). The
        returned object has the following properties:
        <dl>
          <dt><code><strong>start</strong></code></dt>
          <dd>The character (on the given line) at which the token starts.</dd>
          <dt><code><strong>end</strong></code></dt>
          <dd>The character at which the token ends.</dd>
          <dt><code><strong>string</strong></code></dt>
          <dd>The token's string.</dd>
          <dt><code><strong>type</strong></code></dt>
          <dd>The token type the mode assigned
            to the token, such as <code>"keyword"</code>
            or <code>"comment"</code> (may also be null).
          </dd>
          <dt><code><strong>state</strong></code></dt>
          <dd>The mode's state at the end of this token.</dd>
        </dl>
        If <code>precise</code> is true, the token will be guaranteed to be accurate based on recent edits. If false or
        not specified, the token will use cached state information, which will be faster but might not be accurate if
        edits were recently made and highlighting has not yet completed.
      </dd>

      <dt id="getLineTokens"><code><strong>cm.getLineTokens</strong>(line: integer, ?precise: boolean) → array&lt;{start,
        end, string, type, state}&gt;</code></dt>
      <dd>This is similar
        to <a href="#getTokenAt"><code>getTokenAt</code></a>, but
        collects all tokens for a given line into an array. It is much
        cheaper than repeatedly calling <code>getTokenAt</code>, which
        re-parses the part of the line before the token for every call.
      </dd>

      <dt id="getTokenTypeAt"><code><strong>cm.getTokenTypeAt</strong>(pos: {line, ch}) → string</code></dt>
      <dd>This is a (much) cheaper version
        of <a href="#getTokenAt"><code>getTokenAt</code></a> useful for
        when you just need the type of the token at a given position,
        and no other information. Will return <code>null</code> for
        unstyled tokens, and a string, potentially containing multiple
        space-separated style names, otherwise.
      </dd>

      <dt id="getHelpers"><code><strong>cm.getHelpers</strong>(pos: {line, ch}, type: string) →
        array&lt;helper&gt;</code></dt>
      <dd>Fetch the set of applicable helper values for the given
        position. Helpers provide a way to look up functionality
        appropriate for a mode. The <code>type</code> argument provides
        the helper namespace (see
        <a href="#registerHelper"><code>registerHelper</code></a>), in
        which the values will be looked up. When the mode itself has a
        property that corresponds to the <code>type</code>, that
        directly determines the keys that are used to look up the helper
        values (it may be either a single string, or an array of
        strings). Failing that, the mode's <code>helperType</code>
        property and finally the mode's name are used.
      </dd>
      <dd>For example, the JavaScript mode has a
        property <code>fold</code> containing <code>"brace"</code>. When
        the <code>brace-fold</code> addon is loaded, that defines a
        helper named <code>brace</code> in the <code>fold</code>
        namespace. This is then used by
        the <a href="#addon_foldcode"><code>foldcode</code></a> addon to
        figure out that it can use that folding function to fold
        JavaScript code.
      </dd>
      <dd>When any <a href="#registerGlobalHelper">'global'</a>
        helpers are defined for the given namespace, their predicates
        are called on the current mode and editor, and all those that
        declare they are applicable will also be added to the array that
        is returned.
      </dd>

      <dt id="getHelper"><code><strong>cm.getHelper</strong>(pos: {line, ch}, type: string) → helper</code></dt>
      <dd>Returns the first applicable helper value.
        See <a href="#getHelpers"><code>getHelpers</code></a>.
      </dd>

      <dt id="getStateAfter"><code><strong>cm.getStateAfter</strong>(?line: integer, ?precise: boolean) → object</code>
      </dt>
      <dd>Returns the mode's parser state, if any, at the end of the
        given line number. If no line number is given, the state at the
        end of the document is returned. This can be useful for storing
        parsing errors in the state, or getting other kinds of
        contextual information for a line. <code>precise</code> is defined
        as in <code>getTokenAt()</code>.
      </dd>
    </dl>

    <h3 id="api_misc">Miscellaneous methods</h3>

    <dl>
      <dt id="operation"><code><strong>cm.operation</strong>(func: () → any) → any</code></dt>
      <dd>CodeMirror internally buffers changes and only updates its
        DOM structure after it has finished performing some operation.
        If you need to perform a lot of operations on a CodeMirror
        instance, you can call this method with a function argument. It
        will call the function, buffering up all changes, and only doing
        the expensive update after the function returns. This can be a
        lot faster. The return value from this method will be the return
        value of your function.
      </dd>

      <dt id="startOperation"><code><strong>cm.startOperation</strong>()</code></dt>
      <dt id="endOperation"><code><strong>cm.endOperation</strong>()</code></dt>
      <dd>In normal circumstances, use the above <code>operation</code>
        method. But if you want to buffer operations happening asynchronously,
        or that can't all be wrapped in a callback function, you can
        call <code>startOperation</code> to tell CodeMirror to start
        buffering changes, and <code>endOperation</code> to actually
        render all the updates. <em>Be careful:</em> if you use this
        API and forget to call <code>endOperation</code>, the editor will
        just never update.
      </dd>

      <dt id="indentLine"><code><strong>cm.indentLine</strong>(line: integer, ?dir: string|integer)</code></dt>
      <dd>Adjust the indentation of the given line. The second
        argument (which defaults to <code>"smart"</code>) may be one of:
        <dl>
          <dt><code><strong>"prev"</strong></code></dt>
          <dd>Base indentation on the indentation of the previous line.</dd>
          <dt><code><strong>"smart"</strong></code></dt>
          <dd>Use the mode's smart indentation if available, behave
            like <code>"prev"</code> otherwise.
          </dd>
          <dt><code><strong>"add"</strong></code></dt>
          <dd>Increase the indentation of the line by
            one <a href="#option_indentUnit">indent unit</a>.
          </dd>
          <dt><code><strong>"subtract"</strong></code></dt>
          <dd>Reduce the indentation of the line.</dd>
          <dt><code><strong>&lt;integer></strong></code></dt>
          <dd>Add (positive number) or reduce (negative number) the
            indentation by the given amount of spaces.
          </dd>
        </dl>
      </dd>

      <dt id="toggleOverwrite"><code><strong>cm.toggleOverwrite</strong>(?value: boolean)</code></dt>
      <dd>Switches between overwrite and normal insert mode (when not
        given an argument), or sets the overwrite mode to a specific
        state (when given an argument).
      </dd>

      <dt id="isReadOnly"><code><strong>cm.isReadOnly</strong>() → boolean</code></dt>
      <dd>Tells you whether the editor's content can be edited by the
        user.
      </dd>

      <dt id="lineSeparator"><code><strong>doc.lineSeparator</strong>()</code></dt>
      <dd>Returns the preferred line separator string for this
        document, as per the <a href="#option_lineSeparator">option</a>
        by the same name. When that option is <code>null</code>, the
        string <code>"\n"</code> is returned.
      </dd>

      <dt id="execCommand"><code><strong>cm.execCommand</strong>(name: string)</code></dt>
      <dd>Runs the <a href="#commands">command</a> with the given name on the editor.</dd>

      <dt id="posFromIndex"><code><strong>doc.posFromIndex</strong>(index: integer) → {line, ch}</code></dt>
      <dd>Calculates and returns a <code>{line, ch}</code> object for a
        zero-based <code>index</code> who's value is relative to the start of the
        editor's text. If the <code>index</code> is out of range of the text then
        the returned object is clipped to start or end of the text
        respectively.
      </dd>
      <dt id="indexFromPos"><code><strong>doc.indexFromPos</strong>(object: {line, ch}) → integer</code></dt>
      <dd>The reverse of <a href="#posFromIndex"><code>posFromIndex</code></a>.</dd>

      <dt id="focus"><code><strong>cm.focus</strong>()</code></dt>
      <dd>Give the editor focus.</dd>

      <dt id="getInputField"><code><strong>cm.getInputField</strong>() → Element</code></dt>
      <dd>Returns the input field for the editor. Will be a textarea
        or an editable div, depending on the value of
        the <a href="#option_inputStyle"><code>inputStyle</code></a>
        option.
      </dd>
      <dt id="getWrapperElement"><code><strong>cm.getWrapperElement</strong>() → Element</code></dt>
      <dd>Returns the DOM node that represents the editor, and
        controls its size. Remove this from your tree to delete an
        editor instance.
      </dd>
      <dt id="getScrollerElement"><code><strong>cm.getScrollerElement</strong>() → Element</code></dt>
      <dd>Returns the DOM node that is responsible for the scrolling
        of the editor.
      </dd>
      <dt id="getGutterElement"><code><strong>cm.getGutterElement</strong>() → Element</code></dt>
      <dd>Fetches the DOM node that contains the editor gutters.</dd>
    </dl>

    <h3 id="api_static">Static properties</h3>
    <p>The <code>CodeMirror</code> object itself provides
      several useful properties.</p>

    <dl>
      <dt id="version"><code><strong>CodeMirror.version</strong>: string</code></dt>
      <dd>It contains a string that indicates the version of the
        library. This is a triple of
        integers <code>"major.minor.patch"</code>,
        where <code>patch</code> is zero for releases, and something
        else (usually one) for dev snapshots.
      </dd>

      <dt id="fromTextArea"><code><strong>CodeMirror.fromTextArea</strong>(textArea: TextAreaElement, ?config:
        object)</code></dt>
      <dd>This method provides another way to initialize an editor. It
        takes a textarea DOM node as first argument and an optional
        configuration object as second. It will replace the textarea
        with a CodeMirror instance, and wire up the form of that
        textarea (if any) to make sure the editor contents are put into
        the textarea when the form is submitted. The text in the
        textarea will provide the content for the editor. A CodeMirror
        instance created this way has three additional methods:
        <dl>
          <dt id="save"><code><strong>cm.save</strong>()</code></dt>
          <dd>Copy the content of the editor into the textarea.</dd>

          <dt id="toTextArea"><code><strong>cm.toTextArea</strong>()</code></dt>
          <dd>Remove the editor, and restore the original textarea (with
            the editor's current content). If you dynamically create and
            destroy editors made with `fromTextArea`, without destroying
            the form they are part of, you should make sure to call
            `toTextArea` to remove the editor, or its `"submit"` handler
            on the form will cause a memory leak.
          </dd>

          <dt id="getTextArea"><code><strong>cm.getTextArea</strong>() → TextAreaElement</code></dt>
          <dd>Returns the textarea that the instance was based on.</dd>
        </dl>
      </dd>

      <dt id="defaults"><code><strong>CodeMirror.defaults</strong>: object</code></dt>
      <dd>An object containing default values for
        all <a href="#config">options</a>. You can assign to its
        properties to modify defaults (though this won't affect editors
        that have already been created).
      </dd>

      <dt id="defineExtension"><code><strong>CodeMirror.defineExtension</strong>(name: string, value: any)</code></dt>
      <dd>If you want to define extra methods in terms of the
        CodeMirror API, it is possible to
        use <code>defineExtension</code>. This will cause the given
        value (usually a method) to be added to all CodeMirror instances
        created from then on.
      </dd>

      <dt id="defineDocExtension"><code><strong>CodeMirror.defineDocExtension</strong>(name: string, value: any)</code>
      </dt>
      <dd>Like <a href="#defineExtension"><code>defineExtension</code></a>,
        but the method will be added to the interface
        for <a href="#Doc"><code>Doc</code></a> objects instead.
      </dd>

      <dt id="defineOption"><code><strong>CodeMirror.defineOption</strong>(name: string,
        default: any, updateFunc: function)</code></dt>
      <dd>Similarly, <code>defineOption</code> can be used to define new options for
        CodeMirror. The <code>updateFunc</code> will be called with the
        editor instance and the new value when an editor is initialized,
        and whenever the option is modified
        through <a href="#setOption"><code>setOption</code></a>.
      </dd>

      <dt id="defineInitHook"><code><strong>CodeMirror.defineInitHook</strong>(func: function)</code></dt>
      <dd>If your extension just needs to run some
        code whenever a CodeMirror instance is initialized,
        use <code>CodeMirror.defineInitHook</code>. Give it a function as
        its only argument, and from then on, that function will be called
        (with the instance as argument) whenever a new CodeMirror instance
        is initialized.
      </dd>

      <dt id="registerHelper"><code><strong>CodeMirror.registerHelper</strong>(type: string, name: string,
        value: helper)</code></dt>
      <dd>Registers a helper value with the given <code>name</code> in
        the given namespace (<code>type</code>). This is used to define
        functionality that may be looked up by mode. Will create (if it
        doesn't already exist) a property on the <code>CodeMirror</code>
        object for the given <code>type</code>, pointing to an object
        that maps names to values. I.e. after
        doing <code>CodeMirror.registerHelper("hint", "foo",
          myFoo)</code>, the value <code>CodeMirror.hint.foo</code> will
        point to <code>myFoo</code>.
      </dd>

      <dt id="registerGlobalHelper"><code><strong>CodeMirror.registerGlobalHelper</strong>(type: string, name: string,
        predicate: fn(mode, CodeMirror), value: helper)</code></dt>
      <dd>Acts
        like <a href="#registerHelper"><code>registerHelper</code></a>,
        but also registers this helper as 'global', meaning that it will
        be included by <a href="#getHelpers"><code>getHelpers</code></a>
        whenever the given <code>predicate</code> returns true when
        called with the local mode and editor.
      </dd>

      <dt id="Pos"><code><strong>CodeMirror.Pos</strong>(line: integer, ?ch: integer, ?sticky: string)</code></dt>
      <dd>A constructor for the objects that are used to represent
        positions in editor documents. <code>sticky</code> defaults to
        null, but can be set to <code>"before"</code>
        or <code>"after"</code> to make the position explicitly
        associate with the character before or after it.
      </dd>

      <dt id="changeEnd"><code><strong>CodeMirror.changeEnd</strong>(change: object) → {line, ch}</code></dt>
      <dd>Utility function that computes an end position from a change
        (an object with <code>from</code>, <code>to</code>,
        and <code>text</code> properties, as passed to
        various <a href="#event_change">event handlers</a>). The
        returned position will be the end of the changed
        range, <em>after</em> the change is applied.
      </dd>

      <dt id="countColumn"><code><strong>CodeMirror.countColumn</strong>(line: string, index: number, tabSize: number) →
        number</code></dt>
      <dd>Find the column position at a given string index using a given tabsize.</dd>
    </dl>
  </section>

  <section id=addons>
    <h2 id="addons">Addons</h2>

    <p>The <code>addon</code> directory in the distribution contains a
      number of reusable components that implement extra editor
      functionality (on top of extension functions
      like <a href="#defineOption"><code>defineOption</code></a>, <a
        href="#defineExtension"><code>defineExtension</code></a>,
      and <a href="#registerHelper"><code>registerHelper</code></a>). In
      brief, they are:</p>

    <dl>
      <dt id="addon_dialog"><a href="../addon/dialog/dialog.js"><code>dialog/dialog.js</code></a></dt>
      <dd>Provides a very simple way to query users for text input.
        Adds the <strong><code>openDialog(template, callback, options) →
          closeFunction</code></strong> method to CodeMirror instances,
        which can be called with an HTML fragment or a detached DOM
        node that provides the prompt (should include an <code>input</code>
        or <code>button</code> tag), and a callback function that is called
        when the user presses enter. It returns a function <code>closeFunction</code>
        which, if called, will close the dialog immediately.
        <strong><code>openDialog</code></strong> takes the following options:
        <dl>
          <dt><code><strong>closeOnEnter</strong>: bool</code></dt>
          <dd>If true, the dialog will be closed when the user presses
            enter in the input. Defaults to <code>true</code>.
          </dd>
          <dt><code><strong>closeOnBlur</strong>: bool</code></dt>
          <dd>Determines whether the dialog is closed when it loses focus. Defaults to <code>true</code>.</dd>
          <dt><code><strong>onKeyDown</strong>: fn(event: KeyboardEvent, value: string, close: fn()) → bool</code></dt>
          <dd>An event handler that will be called whenever <code>keydown</code> fires in the
            dialog's input. If your callback returns <code>true</code>,
            the dialog will not do any further processing of the event.
          </dd>
          <dt><code><strong>onKeyUp</strong>: fn(event: KeyboardEvent, value: string, close: fn()) → bool</code></dt>
          <dd>Same as <code>onKeyDown</code> but for the
            <code>keyup</code> event.
          </dd>
          <dt><code><strong>onInput</strong>: fn(event: InputEvent, value: string, close: fn()) → bool</code></dt>
          <dd>Same as <code>onKeyDown</code> but for the
            <code>input</code> event.
          </dd>
          <dt><code><strong>onClose</strong>: fn(instance)</code>:</dt>
          <dd>A callback that will be called after the dialog has been closed and
            removed from the DOM. No return value.
          </dd>
        </dl>

        <p>Also adds an <strong><code>openNotification(template, options) →
          closeFunction</code></strong> function that simply shows an HTML
          fragment as a notification at the top of the editor. It takes a
          single option: <code>duration</code>, the amount of time after
          which the notification will be automatically closed. If <code>
            duration</code> is zero, the dialog will not be closed automatically.</p>

        <p>Depends on <code>addon/dialog/dialog.css</code>.</p></dd>

      <dt id="addon_searchcursor"><a href="../addon/search/searchcursor.js"><code>search/searchcursor.js</code></a></dt>
      <dd>Adds the <code>getSearchCursor(query, start, options) →
        cursor</code> method to CodeMirror instances, which can be used
        to implement search/replace functionality. <code>query</code>
        can be a regular expression or a string. <code>start</code>
        provides the starting position of the search. It can be
        a <code>{line, ch}</code> object, or can be left off to default
        to the start of the document. <code>options</code> is an
        optional object, which can contain the property `caseFold:
        false` to disable case folding when mathing a string, or the
        property `multiline: disable` to disable multi-line matching for
        regular expressions (which may help performance). A search
        cursor has the following methods:
        <dl>
          <dt><code><strong>findNext</strong>() → boolean</code></dt>
          <dt><code><strong>findPrevious</strong>() → boolean</code></dt>
          <dd>Search forward or backward from the current position.
            The return value indicates whether a match was found. If
            matching a regular expression, the return value will be the
            array returned by the <code>match</code> method, in case you
            want to extract matched groups.
          </dd>
          <dt><code><strong>from</strong>() → {line, ch}</code></dt>
          <dt><code><strong>to</strong>() → {line, ch}</code></dt>
          <dd>These are only valid when the last call
            to <code>findNext</code> or <code>findPrevious</code> did
            not return false. They will return <code>{line, ch}</code>
            objects pointing at the start and end of the match.
          </dd>
          <dt><code><strong>replace</strong>(text: string, ?origin: string)</code></dt>
          <dd>Replaces the currently found match with the given text
            and adjusts the cursor position to reflect the
            replacement.
          </dd>
        </dl>
      </dd>

      <dt id="addon_search"><a href="../addon/search/search.js"><code>search/search.js</code></a></dt>
      <dd>Implements the search commands. CodeMirror has keys bound to
        these by default, but will not do anything with them unless an
        implementation is provided. Depends
        on <code>searchcursor.js</code>, and will make use
        of <a href="#addon_dialog"><code>openDialog</code></a> when
        available to make prompting for search queries less ugly.
      </dd>

      <dt id="addon_jump-to-line"><a href="../addon/search/jump-to-line.js"><code>search/jump-to-line.js</code></a></dt>
      <dd>Implements a <code>jumpToLine</code> command and binding <code>Alt-G</code> to it.
        Accepts <code>linenumber</code>, <code>+/-linenumber</code>, <code>line:char</code>,
        <code>scroll%</code> and <code>:linenumber</code> formats.
        This will make use of <a href="#addon_dialog"><code>openDialog</code></a>
        when available to make prompting for line number neater.
      </dd>

      <dt id="addon_matchesonscrollbar"><a href="../addon/search/matchesonscrollbar.js"><code>search/matchesonscrollbar.js</code></a>
      </dt>
      <dd>Adds a <code>showMatchesOnScrollbar</code> method to editor
        instances, which should be given a query (string or regular
        expression), optionally a case-fold flag (only applicable for
        strings), and optionally a class name (defaults
        to <code>CodeMirror-search-match</code>) as arguments. When
        called, matches of the given query will be displayed on the
        editor's vertical scrollbar. The method returns an object with
        a <code>clear</code> method that can be called to remove the
        matches. Depends on
        the <a href="#addon_annotatescrollbar"><code>annotatescrollbar</code></a>
        addon, and
        the <a href="../addon/search/matchesonscrollbar.css"><code>matchesonscrollbar.css</code></a>
        file provides a default (transparent yellowish) definition of
        the CSS class applied to the matches. Note that the matches are
        only perfectly aligned if your scrollbar does not have buttons
        at the top and bottom. You can use
        the <a href="#addon_simplescrollbars"><code>simplescrollbar</code></a>
        addon to make sure of this. If this addon is loaded,
        the <a href="#addon_search"><code>search</code></a> addon will
        automatically use it.
      </dd>

      <dt id="addon_matchbrackets"><a href="../addon/edit/matchbrackets.js"><code>edit/matchbrackets.js</code></a></dt>
      <dd>Defines an option <code>matchBrackets</code> which, when set
        to true or an options object, causes matching brackets to be
        highlighted whenever the cursor is next to them. It also adds a
        method <code>matchBrackets</code> that forces this to happen
        once, and a method <code>findMatchingBracket</code> that can be
        used to run the bracket-finding algorithm that this uses
        internally. It takes a start position and an optional config
        object. By default, it will find the match to a matchable
        character either before or after the cursor (preferring the one
        before), but you can control its behavior with these options:
        <dl>
          <dt><strong><code>afterCursor</code></strong></dt>
          <dd>Only use the character after the start position, never the one before it.</dd>
          <dt><strong><code>strict</code></strong></dt>
          <dd>Causes only matches where both brackets are at the same side of the start position to be considered.</dd>
          <dt><strong><code>maxScanLines</code></strong></dt>
          <dd>Stop after scanning this amount of lines without a successful match. Defaults to 1000.</dd>
          <dt><strong><code>maxScanLineLength</code></strong></dt>
          <dd>Ignore lines longer than this. Defaults to 10000.</dd>
        </dl>
      </dd>

      <dt id="addon_closebrackets"><a href="../addon/edit/closebrackets.js"><code>edit/closebrackets.js</code></a></dt>
      <dd>Defines an option <code>autoCloseBrackets</code> that will
        auto-close brackets and quotes when typed. By default, it'll
        auto-close <code>()[]{}''""</code>, but you can pass it a string
        similar to that (containing pairs of matching characters), or an
        object with <code>pairs</code> and
        optionally <code>explode</code> properties to customize
        it. <code>explode</code> should be a similar string that gives
        the pairs of characters that, when enter is pressed between
        them, should have the second character also moved to its own
        line. By default, if the active mode has
        a <code>closeBrackets</code> property, that overrides the
        configuration given in the option. But you can add
        an <code>override</code> property with a truthy value to
        override mode-specific
        configuration. <a href="../demo/closebrackets.html">Demo
          here</a>.
      </dd>

      <dt id="addon_matchtags"><a href="../addon/edit/matchtags.js"><code>edit/matchtags.js</code></a></dt>
      <dd>Defines an option <code>matchTags</code> that, when enabled,
        will cause the tags around the cursor to be highlighted (using
        the <code>CodeMirror-matchingtag</code> class). Also
        defines
        a <a href="#commands">command</a> <code>toMatchingTag</code>,
        which you can bind a key to in order to jump to the tag matching
        the one under the cursor. Depends on
        the <code>addon/fold/xml-fold.js</code>
        addon. <a href="../demo/matchtags.html">Demo here.</a></dd>

      <dt id="addon_trailingspace"><a href="../addon/edit/trailingspace.js"><code>edit/trailingspace.js</code></a></dt>
      <dd>Adds an option <code>showTrailingSpace</code> which, when
        enabled, adds the CSS class <code>cm-trailingspace</code> to
        stretches of whitespace at the end of lines.
        The <a href="../demo/trailingspace.html">demo</a> has a nice
        squiggly underline style for this class.
      </dd>

      <dt id="addon_closetag"><a href="../addon/edit/closetag.js"><code>edit/closetag.js</code></a></dt>
      <dd>Defines an <code>autoCloseTags</code> option that will
        auto-close XML tags when '<code>&gt;</code>' or '<code>/</code>'
        is typed, and
        a <code>closeTag</code> <a href="#commands">command</a> that
        closes the nearest open tag. Depends on
        the <code>fold/xml-fold.js</code> addon. See
        the <a href="../demo/closetag.html">demo</a>.
      </dd>

      <dt id="addon_continuelist"><a href="../addon/edit/continuelist.js"><code>edit/continuelist.js</code></a></dt>
      <dd>Markdown specific. Defines
        a <code>"newlineAndIndentContinueMarkdownList"</code> <a href="#commands">command</a>
        that can be bound to <code>enter</code> to automatically
        insert the leading characters for continuing a list. See
        the <a href="../mode/markdown/index.html">Markdown mode
          demo</a>.
      </dd>

      <dt id="addon_comment"><a href="../addon/comment/comment.js"><code>comment/comment.js</code></a></dt>
      <dd>Addon for commenting and uncommenting code. Adds four
        methods to CodeMirror instances:
        <dl>
          <dt id="toggleComment"><code><strong>toggleComment</strong>(from: {line, ch}, to: {line, ch}, ?options:
            object)</code></dt>
          <dd>Tries to uncomment the current selection, and if that
            fails, line-comments it.
          </dd>
          <dt id="lineComment"><code><strong>lineComment</strong>(from: {line, ch}, to: {line, ch}, ?options:
            object)</code></dt>
          <dd>Set the lines in the given range to be line comments. Will
            fall back to <code>blockComment</code> when no line comment
            style is defined for the mode.
          </dd>
          <dt id="blockComment"><code><strong>blockComment</strong>(from: {line, ch}, to: {line, ch}, ?options: object)</code>
          </dt>
          <dd>Wrap the code in the given range in a block comment. Will
            fall back to <code>lineComment</code> when no block comment
            style is defined for the mode.
          </dd>
          <dt id="uncomment"><code><strong>uncomment</strong>(from: {line, ch}, to: {line, ch}, ?options: object) →
            boolean</code></dt>
          <dd>Try to uncomment the given range.
            Returns <code>true</code> if a comment range was found and
            removed, <code>false</code> otherwise.
          </dd>
        </dl>
        The <code>options</code> object accepted by these methods may
        have the following properties:
        <dl>
          <dt><code>blockCommentStart, blockCommentEnd, blockCommentLead, lineComment: string</code></dt>
          <dd>Override the <a href="#mode_comment">comment string
            properties</a> of the mode with custom comment strings.
          </dd>
          <dt><code><strong>padding</strong>: string</code></dt>
          <dd>A string that will be inserted after opening and leading
            markers, and before closing comment markers. Defaults to a
            single space.
          </dd>
          <dt><code><strong>commentBlankLines</strong>: boolean</code></dt>
          <dd>Whether, when adding line comments, to also comment lines
            that contain only whitespace.
          </dd>
          <dt><code><strong>indent</strong>: boolean</code></dt>
          <dd>When adding line comments and this is turned on, it will
            align the comment block to the current indentation of the
            first line of the block.
          </dd>
          <dt><code><strong>fullLines</strong>: boolean</code></dt>
          <dd>When block commenting, this controls whether the whole
            lines are indented, or only the precise range that is given.
            Defaults to <code>true</code>.
          </dd>
        </dl>
        The addon also defines
        a <code>toggleComment</code> <a href="#commands">command</a>,
        which is a shorthand command for calling
        <code>toggleComment</code> with no options.
      </dd>

      <dt id="addon_foldcode"><a href="../addon/fold/foldcode.js"><code>fold/foldcode.js</code></a></dt>
      <dd>Helps with code folding. Adds a <code>foldCode</code> method
        to editor instances, which will try to do a code fold starting
        at the given line, or unfold the fold that is already present.
        The method takes as first argument the position that should be
        folded (may be a line number or
        a <a href="#Pos"><code>Pos</code></a>), and as second optional
        argument either a range-finder function, or an options object,
        supporting the following properties:
        <dl>
          <dt><code><strong>rangeFinder</strong>: fn(CodeMirror, Pos)</code></dt>
          <dd id="helper_fold_auto">The function that is used to find
            foldable ranges. If this is not directly passed, it will
            default to <code>CodeMirror.fold.auto</code>, which
            uses <a href="#getHelpers"><code>getHelpers</code></a> with
            a <code>"fold"</code> type to find folding functions
            appropriate for the local mode. There are files in
            the <a href="../addon/fold"><code>addon/fold/</code></a>
            directory providing <code>CodeMirror.fold.brace</code>, which
            finds blocks in brace languages (JavaScript, C, Java,
            etc), <code>CodeMirror.fold.indent</code>, for languages where
            indentation determines block structure (Python, Haskell),
            and <code>CodeMirror.fold.xml</code>, for XML-style languages,
            and <code>CodeMirror.fold.comment</code>, for folding comment
            blocks.
          </dd>
          <dt><code><strong>widget</strong>: string|Element</code></dt>
          <dd>The widget to show for folded ranges. Can be either a
            string, in which case it'll become a span with
            class <code>CodeMirror-foldmarker</code>, or a DOM node.
          </dd>
          <dt><code><strong>scanUp</strong>: boolean</code></dt>
          <dd>When true (default is false), the addon will try to find
            foldable ranges on the lines above the current one if there
            isn't an eligible one on the given line.
          </dd>
          <dt><code><strong>minFoldSize</strong>: integer</code></dt>
          <dd>The minimum amount of lines that a fold should span to be
            accepted. Defaults to 0, which also allows single-line
            folds.
          </dd>
        </dl>
        See <a href="../demo/folding.html">the demo</a> for an
        example.
      </dd>

      <dt id="addon_foldgutter"><a href="../addon/fold/foldgutter.js"><code>fold/foldgutter.js</code></a></dt>
      <dd>Provides an option <code>foldGutter</code>, which can be
        used to create a gutter with markers indicating the blocks that
        can be folded. Create a gutter using
        the <a href="#option_gutters"><code>gutters</code></a> option,
        giving it the class <code>CodeMirror-foldgutter</code> or
        something else if you configure the addon to use a different
        class, and this addon will show markers next to folded and
        foldable blocks, and handle clicks in this gutter. Note that
        CSS styles should be applied to make the gutter, and the fold
        markers within it, visible. A default set of CSS styles are
        available in:
        <a href="../addon/fold/foldgutter.css">
          <code>addon/fold/foldgutter.css</code>
        </a>.
        The option
        can be either set to <code>true</code>, or an object containing
        the following optional option fields:
        <dl>
          <dt><code><strong>gutter</strong>: string</code></dt>
          <dd>The CSS class of the gutter. Defaults
            to <code>"CodeMirror-foldgutter"</code>. You will have to
            style this yourself to give it a width (and possibly a
            background). See the default gutter style rules above.
          </dd>
          <dt><code><strong>indicatorOpen</strong>: string | Element</code></dt>
          <dd>A CSS class or DOM element to be used as the marker for
            open, foldable blocks. Defaults
            to <code>"CodeMirror-foldgutter-open"</code>.
          </dd>
          <dt><code><strong>indicatorFolded</strong>: string | Element</code></dt>
          <dd>A CSS class or DOM element to be used as the marker for
            folded blocks. Defaults to <code>"CodeMirror-foldgutter-folded"</code>.
          </dd>
          <dt><code><strong>rangeFinder</strong>: fn(CodeMirror, Pos)</code></dt>
          <dd>The range-finder function to use when determining whether
            something can be folded. When not
            given, <a href="#helper_fold_auto"><code>CodeMirror.fold.auto</code></a>
            will be used as default.
          </dd>
        </dl>
        The <code>foldOptions</code> editor option can be set to an
        object to provide an editor-wide default configuration.
        Demo <a href="../demo/folding.html">here</a>.
      </dd>

      <dt id="addon_runmode"><a href="../addon/runmode/runmode.js"><code>runmode/runmode.js</code></a></dt>
      <dd>Can be used to run a CodeMirror mode over text without
        actually opening an editor instance.
        See <a href="../demo/runmode.html">the demo</a> for an example.
        There are alternate versions of the file available for
        running <a href="../addon/runmode/runmode-standalone.js">stand-alone</a>
        (without including all of CodeMirror) and
        for <a href="../addon/runmode/runmode.node.js">running under
          node.js</a> (see <code>bin/source-highlight</code> for an example of using the latter).
      </dd>

      <dt id="addon_colorize"><a href="../addon/runmode/colorize.js"><code>runmode/colorize.js</code></a></dt>
      <dd>Provides a convenient way to syntax-highlight code snippets
        in a webpage. Depends on
        the <a href="#addon_runmode"><code>runmode</code></a> addon (or
        its standalone variant). Provides
        a <code>CodeMirror.colorize</code> function that can be called
        with an array (or other array-ish collection) of DOM nodes that
        represent the code snippets. By default, it'll get
        all <code>pre</code> tags. Will read the <code>data-lang</code>
        attribute of these nodes to figure out their language, and
        syntax-color their content using the relevant CodeMirror mode
        (you'll have to load the scripts for the relevant modes
        yourself). A second argument may be provided to give a default
        mode, used when no language attribute is found for a node. Used
        in this manual to highlight example code.
      </dd>

      <dt id="addon_overlay"><a href="../addon/mode/overlay.js"><code>mode/overlay.js</code></a></dt>
      <dd>Mode combinator that can be used to extend a mode with an
        'overlay' — a secondary mode is run over the stream, along with
        the base mode, and can color specific pieces of text without
        interfering with the base mode.
        Defines <code>CodeMirror.overlayMode</code>, which is used to
        create such a mode. See <a href="../demo/mustache.html">this
          demo</a> for a detailed example.
      </dd>

      <dt id="addon_multiplex"><a href="../addon/mode/multiplex.js"><code>mode/multiplex.js</code></a></dt>
      <dd>Mode combinator that can be used to easily 'multiplex'
        between several modes.
        Defines <code>CodeMirror.multiplexingMode</code> which, when
        given as first argument a mode object, and as other arguments
        any number of <code>{open, close, mode [, delimStyle, innerStyle, parseDelimiters]}</code>
        objects, will return a mode object that starts parsing using the
        mode passed as first argument, but will switch to another mode
        as soon as it encounters a string that occurs in one of
        the <code>open</code> fields of the passed objects. When in a
        sub-mode, it will go back to the top mode again when
        the <code>close</code> string is encountered.
        Pass <code>"\n"</code> for <code>open</code> or <code>close</code>
        if you want to switch on a blank line.
        <ul>
          <li>When <code>delimStyle</code> is specified, it will be the token
            style returned for the delimiter tokens (as well as
            <code>[delimStyle]-open</code> on the opening token and
            <code>[delimStyle]-close</code> on the closing token).
          </li>
          <li>When <code>innerStyle</code> is specified, it will be the token
            style added for each inner mode token.
          </li>
          <li>When <code>parseDelimiters</code> is true, the content of
            the delimiters will also be passed to the inner mode.
            (And <code>delimStyle</code> is ignored.)
          </li>
        </ul>
        The outer
        mode will not see the content between the delimiters.
        See <a href="../demo/multiplex.html">this demo</a> for an
        example.
      </dd>

      <dt id="addon_show-hint"><a href="../addon/hint/show-hint.js"><code>hint/show-hint.js</code></a></dt>
      <dd>Provides a framework for showing autocompletion hints.
        Defines <code>editor.showHint</code>, which takes an optional
        options object, and pops up a widget that allows the user to
        select a completion. Finding hints is done with a hinting
        functions (the <code>hint</code> option), which is a function
        that take an editor instance and options object, and return
        a <code>{list, from, to}</code> object, where <code>list</code>
        is an array of strings or objects (the completions),
        and <code>from</code> and <code>to</code> give the start and end
        of the token that is being completed as <code>{line, ch}</code>
        objects. An optional <code>selectedHint</code> property (an
        integer) can be added to the completion object to control the
        initially selected hint.
      </dd>
      <dd>If no hinting function is given, the addon will
        use <code>CodeMirror.hint.auto</code>, which
        calls <a href="#getHelpers"><code>getHelpers</code></a> with
        the <code>"hint"</code> type to find applicable hinting
        functions, and tries them one by one. If that fails, it looks
        for a <code>"hintWords"</code> helper to fetch a list of
        completable words for the mode, and
        uses <code>CodeMirror.hint.fromList</code> to complete from
        those.
      </dd>
      <dd>When completions aren't simple strings, they should be
        objects with the following properties:
        <dl>
          <dt><code><strong>text</strong>: string</code></dt>
          <dd>The completion text. This is the only required
            property.
          </dd>
          <dt><code><strong>displayText</strong>: string</code></dt>
          <dd>The text that should be displayed in the menu.</dd>
          <dt><code><strong>className</strong>: string</code></dt>
          <dd>A CSS class name to apply to the completion's line in the
            menu.
          </dd>
          <dt><code><strong>render</strong>: fn(Element, self, data)</code></dt>
          <dd>A method used to create the DOM structure for showing the
            completion by appending it to its first argument.
          </dd>
          <dt><code><strong>hint</strong>: fn(CodeMirror, self, data)</code></dt>
          <dd>A method used to actually apply the completion, instead of
            the default behavior.
          </dd>
          <dt><code><strong>from</strong>: {line, ch}</code></dt>
          <dd>Optional <code>from</code> position that will be used by <code>pick()</code> instead
            of the global one passed with the full list of completions.
          </dd>
          <dt><code><strong>to</strong>: {line, ch}</code></dt>
          <dd>Optional <code>to</code> position that will be used by <code>pick()</code> instead
            of the global one passed with the full list of completions.
          </dd>
        </dl>
      </dd>

      <dd>The plugin understands the following options, which may be
        either passed directly in the argument to <code>showHint</code>,
        or provided by setting an <code>hintOptions</code> editor
        option to an object (the former takes precedence). The options
        object will also be passed along to the hinting function, which
        may understand additional options.
        <dl>
          <dt><code><strong>hint</strong>: function</code></dt>
          <dd>A hinting function, as specified above. It is possible to
            set the <code>async</code> property on a hinting function to
            true, in which case it will be called with
            arguments <code>(cm, callback, ?options)</code>, and the
            completion interface will only be popped up when the hinting
            function calls the callback, passing it the object holding the
            completions.
            The hinting function can also return a promise, and the completion
            interface will only be popped when the promise resolves.
            By default, hinting only works when there is no
            selection. You can give a hinting function
            a <code>supportsSelection</code> property with a truthy value
            to indicate that it supports selections.
          </dd>
          <dt><code><strong>completeSingle</strong>: boolean</code></dt>
          <dd>Determines whether, when only a single completion is
            available, it is completed without showing the dialog.
            Defaults to true.
          </dd>
          <dt><code><strong>alignWithWord</strong>: boolean</code></dt>
          <dd>Whether the pop-up should be horizontally aligned with the
            start of the word (true, default), or with the cursor (false).
          </dd>
          <dt><code><strong>closeOnUnfocus</strong>: boolean</code></dt>
          <dd>When enabled (which is the default), the pop-up will close
            when the editor is unfocused.
          </dd>
          <dt><code><strong>customKeys</strong>: keymap</code></dt>
          <dd>Allows you to provide a custom key map of keys to be active
            when the pop-up is active. The handlers will be called with an
            extra argument, a handle to the completion menu, which
            has <code>moveFocus(n)</code>, <code>setFocus(n)</code>, <code>pick()</code>,
            and <code>close()</code> methods (see the source for details),
            that can be used to change the focused element, pick the
            current element or close the menu. Additionally <code>menuSize()</code>
            can give you access to the size of the current dropdown menu,
            <code>length</code> give you the number of available completions, and
            <code>data</code> give you full access to the completion returned by the
            hinting function.
          </dd>
          <dt><code><strong>extraKeys</strong>: keymap</code></dt>
          <dd>Like <code>customKeys</code> above, but the bindings will
            be added to the set of default bindings, instead of replacing
            them.
          </dd>
        </dl>
        The following events will be fired on the completions object
        during completion:
        <dl>
          <dt><code><strong>"shown"</strong> ()</code></dt>
          <dd>Fired when the pop-up is shown.</dd>
          <dt><code><strong>"select"</strong> (completion, Element)</code></dt>
          <dd>Fired when a completion is selected. Passed the completion
            value (string or object) and the DOM node that represents it
            in the menu.
          </dd>
          <dt><code><strong>"pick"</strong> (completion)</code></dt>
          <dd>Fired when a completion is picked. Passed the completion value
            (string or object).
          </dd>
          <dt><code><strong>"close"</strong> ()</code></dt>
          <dd>Fired when the completion is finished.</dd>
        </dl>
        This addon depends on styles
        from <code>addon/hint/show-hint.css</code>. Check
        out <a href="../demo/complete.html">the demo</a> for an
        example.
      </dd>

      <dt id="addon_javascript-hint"><a href="../addon/hint/javascript-hint.js"><code>hint/javascript-hint.js</code></a>
      </dt>
      <dd>Defines a simple hinting function for JavaScript
        (<code>CodeMirror.hint.javascript</code>) and CoffeeScript
        (<code>CodeMirror.hint.coffeescript</code>) code. This will
        simply use the JavaScript environment that the editor runs in as
        a source of information about objects and their properties.
      </dd>

      <dt id="addon_xml-hint"><a href="../addon/hint/xml-hint.js"><code>hint/xml-hint.js</code></a></dt>
      <dd>Defines <code>CodeMirror.hint.xml</code>, which produces
        hints for XML tagnames, attribute names, and attribute values,
        guided by a <code>schemaInfo</code> option (a property of the
        second argument passed to the hinting function, or the third
        argument passed to <code>CodeMirror.showHint</code>).<br>The
        schema info should be an object mapping tag names to information
        about these tags, with optionally a <code>"!top"</code> property
        containing a list of the names of valid top-level tags. The
        values of the properties should be objects with optional
        properties <code>children</code> (an array of valid child
        element names, omit to simply allow all tags to appear)
        and <code>attrs</code> (an object mapping attribute names
        to <code>null</code> for free-form attributes, and an array of
        valid values for restricted
        attributes). <a href="../demo/xmlcomplete.html">Demo
          here.</a></dd>

      <dt id="addon_html-hint"><a href="../addon/hint/html-hint.js"><code>hint/html-hint.js</code></a></dt>
      <dd>Provides schema info to
        the <a href="#addon_xml-hint">xml-hint</a> addon for HTML
        documents. Defines a schema
        object <code>CodeMirror.htmlSchema</code> that you can pass to
        as a <code>schemaInfo</code> option, and
        a <code>CodeMirror.hint.html</code> hinting function that
        automatically calls <code>CodeMirror.hint.xml</code> with this
        schema data. See
        the <a href="../demo/html5complete.html">demo</a>.
      </dd>

      <dt id="addon_css-hint"><a href="../addon/hint/css-hint.js"><code>hint/css-hint.js</code></a></dt>
      <dd>A hinting function for CSS, SCSS, or LESS code.
        Defines <code>CodeMirror.hint.css</code>.
      </dd>

      <dt id="addon_anyword-hint"><a href="../addon/hint/anyword-hint.js"><code>hint/anyword-hint.js</code></a></dt>
      <dd>A very simple hinting function
        (<code>CodeMirror.hint.anyword</code>) that simply looks for
        words in the nearby code and completes to those. Takes two
        optional options, <code>word</code>, a regular expression that
        matches words (sequences of one or more character),
        and <code>range</code>, which defines how many lines the addon
        should scan when completing (defaults to 500).
      </dd>

      <dt id="addon_sql-hint"><a href="../addon/hint/sql-hint.js"><code>hint/sql-hint.js</code></a></dt>
      <dd>A simple SQL hinter. Defines <code>CodeMirror.hint.sql</code>.
        Takes two optional options, <code>tables</code>, a object with
        table names as keys and array of respective column names as values,
        and <code>defaultTable</code>, a string corresponding to a
        table name in <code>tables</code> for autocompletion.
      </dd>

      <dt id="addon_match-highlighter"><a
        href="../addon/search/match-highlighter.js"><code>search/match-highlighter.js</code></a></dt>
      <dd>Adds a <code>highlightSelectionMatches</code> option that
        can be enabled to highlight all instances of a currently
        selected word. Can be set either to true or to an object
        containing the following options: <code>minChars</code>, for the
        minimum amount of selected characters that triggers a highlight
        (default 2), <code>style</code>, for the style to be used to
        highlight the matches (default <code>"matchhighlight"</code>,
        which will correspond to CSS
        class <code>cm-matchhighlight</code>), <code>trim</code>, which
        controls whether whitespace is trimmed from the selection,
        and <code>showToken</code> which can be set to <code>true</code>
        or to a regexp matching the characters that make up a word. When
        enabled, it causes the current word to be highlighted when
        nothing is selected (defaults to off).
        Demo <a href="../demo/matchhighlighter.html">here</a>.
      </dd>

      <dt id="addon_lint"><a href="../addon/lint/lint.js"><code>lint/lint.js</code></a></dt>
      <dd>Defines an interface component for showing linting warnings,
        with pluggable warning sources
        (see <a href="../addon/lint/html-lint.js"><code>html-lint.js</code></a>,
        <a href="../addon/lint/json-lint.js"><code>json-lint.js</code></a>,
        <a href="../addon/lint/javascript-lint.js"><code>javascript-lint.js</code></a>,
        <a href="../addon/lint/coffeescript-lint.js"><code>coffeescript-lint.js</code></a>,
        and <a href="../addon/lint/css-lint.js"><code>css-lint.js</code></a>
        in the same directory). Defines a <code>lint</code> option that
        can be set to an annotation source (for
        example <code>CodeMirror.lint.javascript</code>), to an options
        object (in which case the <code>getAnnotations</code> field is
        used as annotation source), or simply to <code>true</code>. When
        no annotation source is
        specified, <a href="#getHelper"><code>getHelper</code></a> with
        type <code>"lint"</code> is used to find an annotation function.
        An annotation source function should, when given a document
        string, an options object, and an editor instance, return an
        array of <code>{message, severity, from, to}</code> objects
        representing problems. When the function has
        an <code>async</code> property with a truthy value, it will be
        called with an additional second argument, which is a callback
        to pass the array to.
        The linting function can also return a promise, in that case the linter
        will only be executed when the promise resolves.
        By default, the linter will run (debounced) whenever the document is changed.
        You can pass a <code>lintOnChange: false</code> option to disable that.
        Depends on <code>addon/lint/lint.css</code>. A demo can be
        found <a href="../demo/lint.html">here</a>.
      </dd>

      <dt id="addon_mark-selection"><a
        href="../addon/selection/mark-selection.js"><code>selection/mark-selection.js</code></a></dt>
      <dd>Causes the selected text to be marked with the CSS class
        <code>CodeMirror-selectedtext</code> when the <code>styleSelectedText</code> option
        is enabled. Useful to change the colour of the selection (in addition to the background),
        like in <a href="../demo/markselection.html">this demo</a>.
      </dd>

      <dt id="addon_active-line"><a href="../addon/selection/active-line.js"><code>selection/active-line.js</code></a>
      </dt>
      <dd>Defines a <code>styleActiveLine</code> option that, when
        enabled, gives the wrapper of the line that contains the cursor
        the class <code>CodeMirror-activeline</code>, adds a background
        with the class <code>CodeMirror-activeline-background</code>,
        and adds the class <code>CodeMirror-activeline-gutter</code> to
        the line's gutter space is enabled. The option's value may be a
        boolean or an object specifying the following options:
        <dl>
          <dt><code><strong>nonEmpty</strong>: bool</code></dt>
          <dd>Controls whether single-line selections, or just cursor
            selections, are styled. Defaults to false (only cursor
            selections).
          </dd>
        </dl>
        See the <a href="../demo/activeline.html">demo</a>.
      </dd>

      <dt id="addon_selection-pointer"><a href="../addon/selection/selection-pointer.js"><code>selection/selection-pointer.js</code></a>
      </dt>
      <dd>Defines a <code>selectionPointer</code> option which you can
        use to control the mouse cursor appearance when hovering over
        the selection. It can be set to a string,
        like <code>"pointer"</code>, or to true, in which case
        the <code>"default"</code> (arrow) cursor will be used. You can
        see a demo <a href="../mode/htmlmixed/index.html">here</a>.
      </dd>

      <dt id="addon_loadmode"><a href="../addon/mode/loadmode.js"><code>mode/loadmode.js</code></a></dt>
      <dd>Defines a <code>CodeMirror.requireMode(modename,
        callback)</code> function that will try to load a given mode and
        call the callback when it succeeded. You'll have to
        set <code>CodeMirror.modeURL</code> to a string that mode paths
        can be constructed from, for
        example <code>"mode/%N/%N.js"</code>—the <code>%N</code>'s will
        be replaced with the mode name. Also
        defines <code>CodeMirror.autoLoadMode(instance, mode)</code>,
        which will ensure the given mode is loaded and cause the given
        editor instance to refresh its mode when the loading
        succeeded. See the <a href="../demo/loadmode.html">demo</a>.
      </dd>

      <dt id="addon_meta"><a href="../mode/meta.js"><code>mode/meta.js</code></a></dt>
      <dd>Provides meta-information about all the modes in the
        distribution in a single file.
        Defines <code>CodeMirror.modeInfo</code>, an array of objects
        with <code>{name, mime, mode}</code> properties,
        where <code>name</code> is the human-readable
        name, <code>mime</code> the MIME type, and <code>mode</code> the
        name of the mode file that defines this MIME. There are optional
        properties <code>mimes</code>, which holds an array of MIME
        types for modes with multiple MIMEs associated,
        and <code>ext</code>, which holds an array of file extensions
        associated with this mode. Four convenience
        functions, <code>CodeMirror.findModeByMIME</code>,
        <code>CodeMirror.findModeByExtension</code>,
        <code>CodeMirror.findModeByFileName</code>
        and <code>CodeMirror.findModeByName</code> are provided, which
        return such an object given a MIME, extension, file name or mode name
        string. Note that, for historical reasons, this file resides in the
        top-level <code>mode</code> directory, not
        under <code>addon</code>. <a href="../demo/loadmode.html">Demo</a>.
      </dd>

      <dt id="addon_continuecomment"><a
        href="../addon/comment/continuecomment.js"><code>comment/continuecomment.js</code></a></dt>
      <dd>Adds a <code>continueComments</code> option, which sets whether the
        editor will make the next line continue a comment when you press Enter
        inside a comment block. Can be set to a boolean to enable/disable this
        functionality. Set to a string, it will continue comments using a custom
        shortcut. Set to an object, it will use the <code>key</code> property for
        a custom shortcut and the boolean <code>continueLineComment</code>
        property to determine whether single-line comments should be continued
        (defaulting to <code>true</code>).
      </dd>

      <dt id="addon_placeholder"><a href="../addon/display/placeholder.js"><code>display/placeholder.js</code></a></dt>
      <dd>Adds a <code>placeholder</code> option that can be used to
        make content appear in the editor when it is empty and not
        focused. It can hold either a string or a DOM node. Also gives
        the editor a <code>CodeMirror-empty</code> CSS class whenever it
        doesn't contain any text.
        See <a href="../demo/placeholder.html">the demo</a>.
      </dd>

      <dt id="addon_fullscreen"><a href="../addon/display/fullscreen.js"><code>display/fullscreen.js</code></a></dt>
      <dd>Defines an option <code>fullScreen</code> that, when set
        to <code>true</code>, will make the editor full-screen (as in,
        taking up the whole browser window). Depends
        on <a href="../addon/display/fullscreen.css"><code>fullscreen.css</code></a>. <a href="../demo/fullscreen.html">Demo
          here</a>.
      </dd>

      <dt id="addon_autorefresh"><a href="../addon/display/autorefresh.js"><code>display/autorefresh.js</code></a></dt>
      <dd>This addon can be useful when initializing an editor in a
        hidden DOM node, in cases where it is difficult to
        call <a href="#refresh"><code>refresh</code></a> when the editor
        becomes visible. It defines an option <code>autoRefresh</code>
        which you can set to true to ensure that, if the editor wasn't
        visible on initialization, it will be refreshed the first time
        it becomes visible. This is done by polling every 250
        milliseconds (you can pass a value like <code>{delay:
          500}</code> as the option value to configure this). Note that
        this addon will only refresh the editor <em>once</em> when it
        first becomes visible, and won't take care of further restyling
        and resizing.
      </dd>

      <dt id="addon_simplescrollbars"><a
        href="../addon/scroll/simplescrollbars.js"><code>scroll/simplescrollbars.js</code></a></dt>
      <dd>Defines two additional scrollbar
        models, <code>"simple"</code> and <code>"overlay"</code>
        (see <a href="../demo/simplescrollbars.html">demo</a>) that can
        be selected with
        the <a href="#option_scrollbarStyle"><code>scrollbarStyle</code></a>
        option. Depends
        on <a href="../addon/scroll/simplescrollbars.css"><code>simplescrollbars.css</code></a>,
        which can be further overridden to style your own
        scrollbars.
      </dd>

      <dt id="addon_annotatescrollbar"><a
        href="../addon/scroll/annotatescrollbar.js"><code>scroll/annotatescrollbar.js</code></a></dt>
      <dd>Provides functionality for showing markers on the scrollbar
        to call out certain parts of the document. Adds a
        method <code>annotateScrollbar</code> to editor instances that
        can be called, with a CSS class name as argument, to create a
        set of annotations. The method returns an object
        whose <code>update</code> method can be called with a sorted array
        of <code>{from: Pos, to: Pos}</code> objects marking the ranges
        to be highlighted. To detach the annotations, call the
        object's <code>clear</code> method.
      </dd>

      <dt id="addon_rulers"><a href="../addon/display/rulers.js"><code>display/rulers.js</code></a></dt>
      <dd>Adds a <code>rulers</code> option, which can be used to show
        one or more vertical rulers in the editor. The option, if
        defined, should be given an array of <code>{column [, className,
          color, lineStyle, width]}</code> objects or numbers (which
        indicate a column). The ruler will be displayed at the column
        indicated by the number or the <code>column</code> property.
        The <code>className</code> property can be used to assign a
        custom style to a ruler. <a href="../demo/rulers.html">Demo
          here</a>.
      </dd>

      <dt id="addon_panel"><a href="../addon/display/panel.js"><code>display/panel.js</code></a></dt>
      <dd>Defines an <code>addPanel</code> method for CodeMirror
        instances, which places a DOM node above or below an editor, and
        shrinks the editor to make room for the node. The method takes
        as first argument as DOM node, and as second an optional options
        object. The <code>Panel</code> object returned by this method
        has a <code>clear</code> method that is used to remove the
        panel, and a <code>changed</code> method that can be used to
        notify the addon when the size of the panel's DOM node has
        changed.<br/>
        The method accepts the following options:
        <dl>
          <dt><code><strong>position</strong>: string</code></dt>
          <dd>Controls the position of the newly added panel. The
            following values are recognized:
            <dl>
              <dt><code><strong>top</strong> (default)</code></dt>
              <dd>Adds the panel at the very top.</dd>
              <dt><code><strong>after-top</strong></code></dt>
              <dd>Adds the panel at the bottom of the top panels.</dd>
              <dt><code><strong>bottom</strong></code></dt>
              <dd>Adds the panel at the very bottom.</dd>
              <dt><code><strong>before-bottom</strong></code></dt>
              <dd>Adds the panel at the top of the bottom panels.</dd>
            </dl>
          </dd>
          <dt><code><strong>before</strong>: Panel</code></dt>
          <dd>The new panel will be added before the given panel.</dd>
          <dt><code><strong>after</strong>: Panel</code></dt>
          <dd>The new panel will be added after the given panel.</dd>
          <dt><code><strong>replace</strong>: Panel</code></dt>
          <dd>The new panel will replace the given panel.</dd>
          <dt><code><strong>stable</strong>: bool</code></dt>
          <dd>Whether to scroll the editor to keep the text's vertical
            position stable, when adding a panel above it. Defaults to false.
          </dd>
        </dl>
        When using the <code>after</code>, <code>before</code> or <code>replace</code> options,
        if the panel doesn't exists or has been removed,
        the value of the <code>position</code> option will be used as a fallback.
        <br>
        A demo of the addon is available <a href="../demo/panel.html">here</a>.
      </dd>

      <dt id="addon_hardwrap"><a href="../addon/wrap/hardwrap.js"><code>wrap/hardwrap.js</code></a></dt>
      <dd>Addon to perform hard line wrapping/breaking for paragraphs
        of text. Adds these methods to editor instances:
        <dl>
          <dt><code><strong>wrapParagraph</strong>(?pos: {line, ch}, ?options: object)</code></dt>
          <dd>Wraps the paragraph at the given position.
            If <code>pos</code> is not given, it defaults to the cursor
            position.
          </dd>
          <dt><code><strong>wrapRange</strong>(from: {line, ch}, to: {line, ch}, ?options: object)</code></dt>
          <dd>Wraps the given range as one big paragraph.</dd>
          <dt><code><strong>wrapParagraphsInRange</strong>(from: {line, ch}, to: {line, ch}, ?options: object)</code>
          </dt>
          <dd>Wraps the paragraphs in (and overlapping with) the
            given range individually.
          </dd>
        </dl>
        The following options are recognized:
        <dl>
          <dt><code><strong>paragraphStart</strong>, <strong>paragraphEnd</strong>: RegExp</code></dt>
          <dd>Blank lines are always considered paragraph boundaries.
            These options can be used to specify a pattern that causes
            lines to be considered the start or end of a paragraph.
          </dd>
          <dt><code><strong>column</strong>: number</code></dt>
          <dd>The column to wrap at. Defaults to 80.</dd>
          <dt><code><strong>wrapOn</strong>: RegExp</code></dt>
          <dd>A regular expression that matches only those
            two-character strings that allow wrapping. By default, the
            addon wraps on whitespace and after dash characters.
          </dd>
          <dt><code><strong>killTrailingSpace</strong>: boolean</code></dt>
          <dd>Whether trailing space caused by wrapping should be
            preserved, or deleted. Defaults to true.
          </dd>
        </dl>
        A demo of the addon is available <a href="../demo/hardwrap.html">here</a>.
      </dd>

      <dt id="addon_merge"><a href="../addon/merge/merge.js"><code>merge/merge.js</code></a></dt>
      <dd>Implements an interface for merging changes, using either a
        2-way or a 3-way view. The <code>CodeMirror.MergeView</code>
        constructor takes arguments similar to
        the <a href="#CodeMirror"><code>CodeMirror</code></a>
        constructor, first a node to append the interface to, and then
        an options object. Options are passed through to the editors
        inside the view. These extra options are recognized:
        <dl>
          <dt><code><strong>origLeft</strong></code> and <code><strong>origRight</strong>: string</code></dt>
          <dd>If given these provide original versions of the
            document, which will be shown to the left and right of the
            editor in non-editable CodeMirror instances. The merge
            interface will highlight changes between the editable
            document and the original(s). To create a 2-way (as opposed
            to 3-way) merge view, provide only one of them.
          </dd>
          <dt><code><strong>revertButtons</strong>: boolean</code></dt>
          <dd>Determines whether buttons that allow the user to revert
            changes are shown. Defaults to true.
          </dd>
          <dt><code><strong>revertChunk</strong>: fn(mv: MergeView, from: CodeMirror, fromStart: Pos, fromEnd: Pos, to:
            CodeMirror, toStart: Pos, toEnd: Pos)</code></dt>
          <dd>Can be used to define custom behavior when the user
            reverts a changed chunk.
          </dd>
          <dt><code><strong>connect</strong>: string</code></dt>
          <dd>Sets the style used to connect changed chunks of code.
            By default, connectors are drawn. When this is set
            to <code>"align"</code>, the smaller chunk is padded to
            align with the bigger chunk instead.
          </dd>
          <dt><code><strong>collapseIdentical</strong>: boolean|number</code></dt>
          <dd>When true (default is false), stretches of unchanged
            text will be collapsed. When a number is given, this
            indicates the amount of lines to leave visible around such
            stretches (which defaults to 2).
          </dd>
          <dt><code><strong>allowEditingOriginals</strong>: boolean</code></dt>
          <dd>Determines whether the original editor allows editing.
            Defaults to false.
          </dd>
          <dt><code><strong>showDifferences</strong>: boolean</code></dt>
          <dd>When true (the default), changed pieces of text are
            highlighted.
          </dd>
          <dt><code><strong>chunkClassLocation</strong>: string|Array</code></dt>
          <dd>By default the chunk highlights are added
            using <a href="#addLineClass"><code>addLineClass</code></a>
            with "background". Override this to customize it to be any
            valid `where` parameter or an Array of valid `where`
            parameters.
          </dd>
        </dl>
        The addon also defines commands <code>"goNextDiff"</code>
        and <code>"goPrevDiff"</code> to quickly jump to the next
        changed chunk. <a href="../demo/merge.html">Demo
          here</a>.
      </dd>

      <dt id="addon_tern"><a href="../addon/tern/tern.js"><code>tern/tern.js</code></a></dt>
      <dd>Provides integration with
        the <a href="http://ternjs.net">Tern</a> JavaScript analysis
        engine, for completion, definition finding, and minor
        refactoring help. See the <a href="../demo/tern.html">demo</a>
        for a very simple integration. For more involved scenarios, see
        the comments at the top of
        the <a href="../addon/tern/tern.js">addon</a> and the
        implementation of the
        (multi-file) <a href="http://ternjs.net/doc/demo.html">demonstration
          on the Tern website</a>.
      </dd>
    </dl>
  </section>

  <section id=modeapi>
    <h2>Writing CodeMirror Modes</h2>

    <p>Modes typically consist of a single JavaScript file. This file
      defines, in the simplest case, a lexer (tokenizer) for your
      language—a function that takes a character stream as input,
      advances it past a token, and returns a style for that token. More
      advanced modes can also handle indentation for the language.</p>

    <p>This section describes the low-level mode interface. Many modes
      are written directly against this, since it offers a lot of
      control, but for a quick mode definition, you might want to use
      the <a href="../demo/simplemode.html">simple mode addon</a>.</p>

    <p id="defineMode">The mode script should
      call <code><strong>CodeMirror.defineMode</strong></code> to
      register itself with CodeMirror. This function takes two
      arguments. The first should be the name of the mode, for which you
      should use a lowercase string, preferably one that is also the
      name of the files that define the mode (i.e. <code>"xml"</code> is
      defined in <code>xml.js</code>). The second argument should be a
      function that, given a CodeMirror configuration object (the thing
      passed to the <code>CodeMirror</code> function) and an optional
      mode configuration object (as in
      the <a href="#option_mode"><code>mode</code></a> option), returns
      a mode object.</p>

    <p>Typically, you should use this second argument
      to <code>defineMode</code> as your module scope function (modes
      should not leak anything into the global scope!), i.e. write your
      whole mode inside this function.</p>

    <p>The main responsibility of a mode script is <em>parsing</em>
      the content of the editor. Depending on the language and the
      amount of functionality desired, this can be done in really easy
      or extremely complicated ways. Some parsers can be stateless,
      meaning that they look at one element (<em>token</em>) of the code
      at a time, with no memory of what came before. Most, however, will
      need to remember something. This is done by using a <em>state
        object</em>, which is an object that is always passed when
      reading a token, and which can be mutated by the tokenizer.</p>

    <p id="startState">Modes that use a state must define
      a <code><strong>startState</strong></code> method on their mode
      object. This is a function of no arguments that produces a state
      object to be used at the start of a document.</p>

    <p id="token">The most important part of a mode object is
      its <code><strong>token</strong>(stream, state)</code> method. All
      modes must define this method. It should read one token from the
      stream it is given as an argument, optionally update its state,
      and return a style string, or <code>null</code> for tokens that do
      not have to be styled. For your styles, you are encouraged to use
      the 'standard' names defined in the themes (without
      the <code>cm-</code> prefix). If that fails, it is also possible
      to come up with your own and write your own CSS theme file.
    <p>

    <p id="token_style_line">A typical token string would
      be <code>"variable"</code> or <code>"comment"</code>. Multiple
      styles can be returned (separated by spaces), for
      example <code>"string error"</code> for a thing that looks like a
      string but is invalid somehow (say, missing its closing quote).
      When a style is prefixed by <code>"line-"</code>
      or <code>"line-background-"</code>, the style will be applied to
      the whole line, analogous to what
      the <a href="#addLineClass"><code>addLineClass</code></a> method
      does—styling the <code>"text"</code> in the simple case, and
      the <code>"background"</code> element
      when <code>"line-background-"</code> is prefixed.</p>

    <p id="StringStream">The stream object that's passed
      to <code>token</code> encapsulates a line of code (tokens may
      never span lines) and our current position in that line. It has
      the following API:</p>

    <dl>
      <dt><code><strong>eol</strong>() → boolean</code></dt>
      <dd>Returns true only if the stream is at the end of the
        line.
      </dd>
      <dt><code><strong>sol</strong>() → boolean</code></dt>
      <dd>Returns true only if the stream is at the start of the
        line.
      </dd>

      <dt><code><strong>peek</strong>() → string</code></dt>
      <dd>Returns the next character in the stream without advancing
        it. Will return a <code>null</code> at the end of the
        line.
      </dd>
      <dt><code><strong>next</strong>() → string</code></dt>
      <dd>Returns the next character in the stream and advances it.
        Also returns <code>null</code> when no more characters are
        available.
      </dd>

      <dt><code><strong>eat</strong>(match: string|regexp|function(char: string) → boolean) → string</code></dt>
      <dd><code>match</code> can be a character, a regular expression,
        or a function that takes a character and returns a boolean. If
        the next character in the stream 'matches' the given argument,
        it is consumed and returned. Otherwise, <code>undefined</code>
        is returned.
      </dd>
      <dt><code><strong>eatWhile</strong>(match: string|regexp|function(char: string) → boolean) → boolean</code></dt>
      <dd>Repeatedly calls <code>eat</code> with the given argument,
        until it fails. Returns true if any characters were eaten.
      </dd>
      <dt><code><strong>eatSpace</strong>() → boolean</code></dt>
      <dd>Shortcut for <code>eatWhile</code> when matching
        white-space.
      </dd>
      <dt><code><strong>skipToEnd</strong>()</code></dt>
      <dd>Moves the position to the end of the line.</dd>
      <dt><code><strong>skipTo</strong>(str: string) → boolean</code></dt>
      <dd>Skips to the start of the next occurrence of the given string, if
        found on the current line (doesn't advance the stream if the
        string does not occur on the line). Returns true if the
        string was found.
      </dd>
      <dt><code><strong>match</strong>(pattern: string, ?consume: boolean, ?caseFold: boolean) → boolean</code></dt>
      <dt><code><strong>match</strong>(pattern: regexp, ?consume: boolean) → array&lt;string&gt;</code></dt>
      <dd>Act like a
        multi-character <code>eat</code>—if <code>consume</code> is true
        or not given—or a look-ahead that doesn't update the stream
        position—if it is false. <code>pattern</code> can be either a
        string or a regular expression starting with <code>^</code>.
        When it is a string, <code>caseFold</code> can be set to true to
        make the match case-insensitive. When successfully matching a
        regular expression, the returned value will be the array
        returned by <code>match</code>, in case you need to extract
        matched groups.
      </dd>

      <dt><code><strong>backUp</strong>(n: integer)</code></dt>
      <dd>Backs up the stream <code>n</code> characters. Backing it up
        further than the start of the current token will cause things to
        break, so be careful.
      </dd>
      <dt><code><strong>column</strong>() → integer</code></dt>
      <dd>Returns the column (taking into account tabs) at which the
        current token starts.
      </dd>
      <dt><code><strong>indentation</strong>() → integer</code></dt>
      <dd>Tells you how far the current line has been indented, in
        spaces. Corrects for tab characters.
      </dd>

      <dt><code><strong>current</strong>() → string</code></dt>
      <dd>Get the string between the start of the current token and
        the current stream position.
      </dd>

      <dt><code><strong>lookAhead</strong>(n: number) → ?string</code></dt>
      <dd>Get the line <code>n</code> (&gt;0) lines after the current
        one, in order to scan ahead across line boundaries. Note that
        you want to do this carefully, since looking far ahead will make
        mode state caching much less effective.
      </dd>

      <dt><code><strong>baseToken</strong>() → ?{type: ?string, size: number}</code></dt>
      <dd>Modes added
        through <a href="#addOverlay"><code>addOverlay</code></a>
        (and <em>only</em> such modes) can use this method to inspect
        the current token produced by the underlying mode.
      </dd>
    </dl>

    <p id="blankLine">By default, blank lines are simply skipped when
      tokenizing a document. For languages that have significant blank
      lines, you can define
      a <code><strong>blankLine</strong>(state)</code> method on your
      mode that will get called whenever a blank line is passed over, so
      that it can update the parser state.</p>

    <p id="copyState">Because state object are mutated, and CodeMirror
      needs to keep valid versions of a state around so that it can
      restart a parse at any line, copies must be made of state objects.
      The default algorithm used is that a new state object is created,
      which gets all the properties of the old object. Any properties
      which hold arrays get a copy of these arrays (since arrays tend to
      be used as mutable stacks). When this is not correct, for example
      because a mode mutates non-array properties of its state object, a
      mode object should define
      a <code><strong>copyState</strong></code> method, which is given a
      state and should return a safe copy of that state.</p>

    <p id="indent">If you want your mode to provide smart indentation
      (through the <a href="#indentLine"><code>indentLine</code></a>
      method and the <code>indentAuto</code>
      and <code>newlineAndIndent</code> commands, to which keys can be
      <a href="#option_extraKeys">bound</a>), you must define
      an <code><strong>indent</strong>(state, textAfter)</code> method
      on your mode object.</p>

    <p>The indentation method should inspect the given state object,
      and optionally the <code>textAfter</code> string, which contains
      the text on the line that is being indented, and return an
      integer, the amount of spaces to indent. It should usually take
      the <a href="#option_indentUnit"><code>indentUnit</code></a>
      option into account. An indentation method may
      return <code>CodeMirror.Pass</code> to indicate that it
      could not come up with a precise indentation.</p>

    <p id="mode_comment">To work well with
      the <a href="#addon_comment">commenting addon</a>, a mode may
      define <code><strong>lineComment</strong></code> (string that
      starts a line
      comment), <code><strong>blockCommentStart</strong></code>, <code><strong>blockCommentEnd</strong></code>
      (strings that start and end block comments),
      and <code>blockCommentLead</code> (a string to put at the start of
      continued lines in a block comment). All of these are
      optional.</p>

    <p id="electricChars">Finally, a mode may define either
      an <code>electricChars</code> or an <code>electricInput</code>
      property, which are used to automatically reindent the line when
      certain patterns are typed and
      the <a href="#option_electricChars"><code>electricChars</code></a>
      option is enabled. <code>electricChars</code> may be a string, and
      will trigger a reindent whenever one of the characters in that
      string are typed. Often, it is more appropriate to
      use <code>electricInput</code>, which should hold a regular
      expression, and will trigger indentation when the part of the
      line <em>before</em> the cursor matches the expression. It should
      usually end with a <code>$</code> character, so that it only
      matches when the indentation-changing pattern was just typed, not when something was
      typed after the pattern.</p>

    <p>So, to summarize, a mode <em>must</em> provide
      a <code>token</code> method, and it <em>may</em>
      provide <code>startState</code>, <code>copyState</code>,
      and <code>indent</code> methods. For an example of a trivial mode,
      see the <a href="../mode/diff/diff.js">diff mode</a>, for a more
      involved example, see the <a href="../mode/clike/clike.js">C-like
        mode</a>.</p>

    <p>Sometimes, it is useful for modes to <em>nest</em>—to have one
      mode delegate work to another mode. An example of this kind of
      mode is the <a href="../mode/htmlmixed/htmlmixed.js">mixed-mode HTML
        mode</a>. To implement such nesting, it is usually necessary to
      create mode objects and copy states yourself. To create a mode
      object, there are <code>CodeMirror.getMode(options,
        parserConfig)</code>, where the first argument is a configuration
      object as passed to the mode constructor function, and the second
      argument is a mode specification as in
      the <a href="#option_mode"><code>mode</code></a> option. To copy a
      state object, call <code>CodeMirror.copyState(mode, state)</code>,
      where <code>mode</code> is the mode that created the given
      state.</p>

    <p id="innerMode">In a nested mode, it is recommended to add an
      extra method, <code><strong>innerMode</strong></code> which, given
      a state object, returns a <code>{state, mode}</code> object with
      the inner mode and its state for the current position. These are
      used by utility scripts such as the <a href="#addon_closetag">tag
        closer</a> to get context information. Use
      the <code>CodeMirror.innerMode</code> helper function to, starting
      from a mode and a state, recursively walk down to the innermost
      mode and state.</p>

    <p>To make indentation work properly in a nested parser, it is
      advisable to give the <code>startState</code> method of modes that
      are intended to be nested an optional argument that provides the
      base indentation for the block of code. The JavaScript and CSS
      parser do this, for example, to allow JavaScript and CSS code
      inside the mixed-mode HTML mode to be properly indented.</p>

    <p id="defineMIME">It is possible, and encouraged, to associate
      your mode, or a certain configuration of your mode, with
      a <a href="http://en.wikipedia.org/wiki/MIME">MIME</a> type. For
      example, the JavaScript mode associates itself
      with <code>text/javascript</code>, and its JSON variant
      with <code>application/json</code>. To do this,
      call <code><strong>CodeMirror.defineMIME</strong>(mime,
        modeSpec)</code>, where <code>modeSpec</code> can be a string or
      object specifying a mode, as in
      the <a href="#option_mode"><code>mode</code></a> option.</p>

    <p>If a mode specification wants to add some properties to the
      resulting mode object, typically for use
      with <a href="#getHelpers"><code>getHelpers</code></a>, it may
      contain a <code>modeProps</code> property, which holds an object.
      This object's properties will be copied to the actual mode
      object.</p>

    <p id="extendMode">Sometimes, it is useful to add or override mode
      object properties from external code.
      The <code><strong>CodeMirror.extendMode</strong></code> function
      can be used to add properties to mode objects produced for a
      specific mode. Its first argument is the name of the mode, its
      second an object that specifies the properties that should be
      added. This is mostly useful to add utilities that can later be
      looked up through <a href="#getMode"><code>getMode</code></a>.</p>
  </section>

  <section id="vimapi">
    <h2>VIM Mode API</h2>

    <p>CodeMirror has a robust VIM mode that attempts to faithfully
      emulate VIM's most useful features. It can be enabled by
      including <a href="../keymap/vim.js"><code>keymap/vim.js</code>
      </a> and setting the <code>keyMap</code> option to
      <code>"vim"</code>.</p>

    <h3 id="vimapi_configuration">Configuration</h3>

    <p>VIM mode accepts configuration options for customizing
      behavior at run time. These methods can be called at any time
      and will affect all existing CodeMirror instances unless
      specified otherwise. The methods are exposed on the
      <code><strong>CodeMirror.Vim</strong></code> object.</p>

    <dl>
      <dt id="vimapi_setOption"><code><strong>setOption(name: string, value: any, ?cm: CodeMirror, ?cfg:
        object)</strong></code></dt>
      <dd>Sets the value of a VIM option. <code>name</code> should
        be the name of an option. If <code>cfg.scope</code> is not set
        and <code>cm</code> is provided, then sets the global and
        instance values of the option. Otherwise, sets either the
        global or instance value of the option depending on whether
        <code>cfg.scope</code> is <code>global</code> or
        <code>local</code>.
      </dd>
      <dt id="vimapi_getOption"><code><strong>getOption(name: string, ?cm: CodeMirror: ?cfg: object)</strong></code>
      </dt>
      <dd>Gets the current value of a VIM option. If
        <code>cfg.scope</code> is not set and <code>cm</code> is
        provided, then gets the instance value of the option, falling
        back to the global value if not set. If <code>cfg.scope</code> is provided, then gets the <code>global</code> or
        <code>local</code> value without checking the other.
      </dd>

      <dt id="vimapi_map"><code><strong>map(lhs: string, rhs: string, ?context: string)</strong></code></dt>
      <dd>Maps a key sequence to another key sequence. Implements
        VIM's <code>:map</code> command. To map ; to : in VIM would be
        <code><strong>:map ; :</strong></code>. That would translate to
        <code><strong>CodeMirror.Vim.map(';', ':');</strong></code>.
        The <code>context</code> can be <code>normal</code>,
        <code>visual</code>, or <code>insert</code>, which correspond
        to <code>:nmap</code>, <code>:vmap</code>, and
        <code>:imap</code>
        respectively.
      </dd>

      <dt id="vimapi_mapCommand"><code><strong>mapCommand(keys: string, type: string, name: string, ?args: object,
        ?extra: object)</strong></code></dt>
      <dd>Maps a key sequence to a <code>motion</code>,
        <code>operator</code>, or <code>action</code> type command.
        The args object is passed through to the command when it is
        invoked by the provided key sequence.
        <code>extras.context</code> can be <code>normal</code>,
        <code>visual</code>, or <code>insert</code>, to map the key
        sequence only in the corresponding mode.
        <code>extras.isEdit</code> is applicable only to actions,
        determining whether it is recorded for replay for the
        <code>.</code> single-repeat command.
    </dl>

    <h3 id="vimapi_extending">Extending VIM</h3>

    <p>CodeMirror's VIM mode implements a large subset of VIM's core
      editing functionality. But since there's always more to be
      desired, there is a set of APIs for extending VIM's
      functionality. As with the configuration API, the methods are
      exposed on <code><strong>CodeMirror.Vim</strong></code> and may
      be called at any time.</p>

    <dl>
      <dt id="vimapi_defineOption"><code><strong>defineOption(name: string, default: any, type: string, ?aliases: array&lt;string&gt;,
        ?callback: function (?value: any, ?cm: CodeMirror) → ?any)</strong></code></dt>
      <dd>Defines a VIM style option and makes it available to the
        <code>:set</code> command. Type can be <code>boolean</code> or
        <code>string</code>, used for validation and by
        <code>:set</code> to determine which syntax to accept. If a
        <code>callback</code> is passed in, VIM does not store the value of the
        option itself, but instead uses the callback as a setter/getter. If the
        first argument to the callback is <code>undefined</code>, then the
        callback should return the value of the option. Otherwise, it should set
        instead. Since VIM options have global and instance values, whether a
        <code>CodeMirror</code> instance is passed in denotes whether the global
        or local value should be used. Consequently, it's possible for the
        callback to be called twice for a single <code>setOption</code> or
        <code>getOption</code> call. Note that right now, VIM does not support
        defining buffer-local options that do not have global values. If an
        option should not have a global value, either always ignore the
        <code>cm</code> parameter in the callback, or always pass in a
        <code>cfg.scope</code> to <code>setOption</code> and
        <code>getOption</code>.
      </dd>

      <dt id="vimapi_defineMotion"><code><strong>defineMotion(name: string, fn: function(cm: CodeMirror, head: {line,
        ch}, ?motionArgs: object}) → {line, ch})</strong></code></dt>
      <dd>Defines a motion command for VIM. The motion should return
        the desired result position of the cursor. <code>head</code>
        is the current position of the cursor. It can differ from
        <code>cm.getCursor('head')</code> if VIM is in visual mode.
        <code>motionArgs</code> is the object passed into
        <strong><code>mapCommand()</code></strong>.
      </dd>

      <dt id="vimapi_defineOperator"><strong><code>defineOperator(name: string, fn: function(cm: CodeMirror,
        ?operatorArgs: object, ranges: array&lt;{anchor, head}&gt;) → ?{line, ch})</code></strong></dt>
      <dd>Defines an operator command, similar to <strong><code>
        defineMotion</code></strong>. <code>ranges</code> is the range
        of text the operator should operate on. If the cursor should
        be set to a certain position after the operation finishes, it
        can return a cursor object.
      </dd>

      <dt id="vimapi_defineActon"><strong><code>defineAction(name: string, fn: function(cm: CodeMirror, ?actionArgs:
        object))</code></strong></dt>
      <dd>Defines an action command, similar to
        <strong><code>defineMotion</code></strong>. Action commands
        can have arbitrary behavior, making them more flexible than
        motions and operators, at the loss of orthogonality.
      </dd>

      <dt id="vimapi_defineEx"><strong><code>defineEx(name: string, ?prefix: string, fn: function(cm: CodeMirror,
        ?params: object))</code></strong></dt>
      <dd>Defines an Ex command, and maps it to <code>:name</code>.
        If a prefix is provided, it, and any prefixed substring of the
        <code>name</code> beginning with the <code>prefix</code> can
        be used to invoke the command. If the <code>prefix</code> is
        falsy, then <code>name</code> is used as the prefix. <code>
          params.argString</code> contains the part of the prompted
        string after the command name. <code>params.args</code> is
        <code>params.argString</code> split by whitespace. If the
        command was prefixed with a
        <code><strong><a href="http://vimdoc.sourceforge.net/htmldoc/cmdline.html#cmdline-ranges">line
          range</a></strong></code>,
        <code>params.line</code> and <code>params.lineEnd</code> will
        be set.
    </dl>

  </section>

</article>

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